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In-Line Diffused Aeration to Reduce THMs in Distribution Piping

This post from University of New Hampshire's M.R. Collins is a continuation of a project update originally shared in our Technology News newsletter. 

Several methods exist for controlling THM formation, including reducing natural organic matter (NOM) prior to chlorine disinfection, and using an alternate disinfectant such as ozone, chloramines, or UV. Using these disinfectants will prevent or reduce the formation of THMs, but could facilitate the production of other potentially harmful byproducts.  Also, using ozone or UV as a disinfectant will not provide a residual in the distribution system (USEPA, 1981 & USEPA, 1999).  While effective at reducing THM formation, changing or upgrading the water treatment plant to include these control techniques could be costly and negatively affect other plant processes.

Posttreatment aeration is another strategy to control THMs, and involves removing the THMs after formation.  Countercurrent packed towers, diffused aeration in open reactors, and spray aeration in storage tanks are all viable aeration methods to remove THMs (USEPA, 1981 and Brooke & Collins, 2011).  While the above methods are viable and have been applied in the field, all require depressurization of the water, and are limited in terms of placement in the water distribution system.  Placement in the distribution system is important since THMs continue to form in the system, and often exceed regulations when at the far end of the system.  This research explores both vertical in-line diffused aeration (VILDA) and horizontal in-line diffused aeration (HILDA) to reduce THMs, which has the potential to be cost effective and conveniently placed where needed in the distribution system.

A schematic of an in-line diffused aeration system is depicted in Figure 1. The basic components consist of an air compressor, air-water reactor, air injector, air release system and associated air and water flow meters. The basic difference between VILDA and HILDA systems is the configuration of the air-water reactor. The VILDA system will utilize a countercurrent arrangement where air is injected in the bottom of the vertical reactor while the water enters at the top of the reactor. The HILDA will have air and water flowing concurrently through the horizontal reactor.

Figure 1. Schematic of basic in-line diffused aeration system. 

The most efficient air-water reactor is one where equilibrium or saturation THM removals can be achieved. The work of Matter-Müller et al. (1981) provides a mass balance method which allows equilibrium or saturation THM removal values to be predicted as depicted in Equation 1:

Equation 1:                             

where QG = the gas flow in (m3/s), Hcc = the dimensionless Henry’s law constant of compound, and QL= the liquid flow rate (m3/s). Hence, the higher the air/water ratio, the greater the removals of THMs.

For Equation 1 to be applicable to distribution piping conditions, the Henry’s Law Constant will have to be adjusted for both temperature and pressure. The former has been well documented in the literature but the latter had to be determined during this research. Basically, a second order relationship as shown in Equation 2 was used to correct for pressure (Zwerneman, 2012).

Equation 2:                                

where Hcc  = the dimensionless Henry’s law constant at system pressure, Hcc,o   = the dimensionless Henry’s law constant at atmospheric pressure, P = the system pressure (psi), and k= the experimentally determined rate constant (psi-1).

HILDA REACTOR DESIGN. The most problematic concern with a HILDA system was to configure an air-water reactor where equilibrium or saturation conditions will be achieved since injected air in a horizontal pipeline will have a strong tendency to raise to the top of the pipe and not be mixed with the water sufficiently to reach saturation. Through trial and error, Komax static mixers were determined to provide adequate air-water mixing to approach saturation removal conditions provided fluid turbulence or mixing intensity was high enough. A modified Reynolds Number (Re’) was developed to capture the magnitude of fluid momentum and mixing intensity and can be seen in Equation 3 (McCowan, 2015).

Equation 3:                                           

where, v= velocity of water (ft/s), d=pipe diameter (ft), Lm=length of reactor (ft), and v=kinematic viscosity (ft2/s). Figure 2 shows a graphical representation of % removal vs. Re’ at 10:1 and 20:1 A:W ratios.  Re’ appears to be a good indicator of when saturation values are achieved and could be used to design of the HILDA reactor.

Figure 2. HILDA model predictions of THM removals for various A:W ratios as a function of modified Reynolds Number.

VILDA REACTOR DESIGN. Equilibrium or saturation removal conditions in a VILDA system is easier to achieve than with a HILDA system although a HILDA system could be easier to install in the field. The countercurrent flows in a VILDA reactor encourages adequate contact time between the air bubbles and bulk water to achieve saturation conditions quickly as depicted in Figure 3. Basically, in-line diffused aeration is a fast treatment process.

Figure 3. Influence of A:W ratios on VILDA EBCTs required to reach saturation THM removals.

SUMMARY. Both HILDA and VILDA have shown potential to achieve significant reductions in THMs in distribution pipelines especially if the most dominant species is chloroform. Research on bench and pilot scale versions of these posttreatment aeration systems have resulted in prediction models that could be used to design HILDA and VILDA reactors in the field. Field assessment and treatment verification of this innovative technology are currently being explored and developed. Opportunities to participate in these assessment studies are still available. Please inquire within.


Brooke, E. & Collins M.R., 2011. Posttreatment Aeration to Reduce THMs. Journal AWWA, 103:10.

Komax Systems, Inc. Triple Action Static Mixer. (accessed 3/31/15).

Matter-Müller, C.; Gujer, G.; Giger, G., 1981. Transfer of Volatile Substances from Water to the Atmosphere. Water Research, 15:1271.

McCowan, M.L.,2015. Developing a Horizontal In-Line Diffused Aeration System for Removing Trihalomethanes from Water Distribution Mains. Master’s Thesis, University of New Hampshire, Durham, N.H.

USEPA (United States Environmental Protection Agency), 1999.Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.

USEPA (United States Environmental Protection Agency), 1981. Treatment Techniques for Controlling Trihalomethanes in Drinking Water. EPA/600/2-81/156, Washington, DC.

Zwerneman, J., 2012. Investigating the Effect of System Pressure on Trihalomethane Post-Treatment Diffused Aeration. Master’s Thesis, University of New Hampshire, Durham, N.H.

Common Distribution System Deficiencies

This article was first published in the Winter 2012 issue of Spigot News, the Ohio EPA's drinking water program newsletter. Many thanks for allowing us to republish it! You may also be interested in the articles Common Source Water Deficiencies and Common Treatment Deficiencies

This article is a continuation of the series on common deficiencies, covering source, treatment and distribution deficiencies. This article covers different aspects of the distribution system, including cross-connection, backflow, depressurization events, water age and infrastructure deterioration. 

A “cross-connection” occurs in areas of the plumbing system where non-potable water comes in contact with potable water. There are two types of cross-connections: direct and indirect cross-connections. 

Direct cross-connections – the potable system is permanently connected to a non-potable system (for example a submerged inlet pipe for a chemical feed system). 

Indirect cross-connections – there is a potential for a connection of the potable system to a non-potable system (for example, a garden hose connected to an outside hose bid without a vacuum breaker or a bidet with a douche sprayer or jet that fills the bowl below the rim). 

Establish cross-connection control ordinances for municipalities with diligent inspections of new and existing plumbing to prevent possible cross-connection issues. These issues may be identified during a sanitary survey or when real estate is bought and/or sold within the municipality. 

Backflow and Backsiphonage
A “backflow event” is when non-potable water is forced by pressure into the potable water supply due to a direct cross-connection. All distribution systems must maintain a minimum pressure of 20 psig and a 35 psig working pressure during all water demands including fires. Distribution systems that fall below these minimum pressures may experience a backflow event if an overpowering pressure differential is experienced by a competing cross-connection within the system. 

A “backsiphonage event” is when water flows backward in the water distribution system from a vessel or other contamination source because the distribution system has lost, created or reduced pressure. 

Backflow devices (backflow preventers, double check valves, testable reduced pressure zone device, etc.) are required on certain businesses that pose the most threat to a potable water system, but municipalities can require all businesses and homes within their jurisdictions to install and inspect backflow devices every 12 months. Another preventative measure may be to conduct a hydraulic assessment of the distribution system to identify those areas at most risk of a backflow event. Once identified, these areas can be targeted for improvement.  

Depressurization Events
System-wide depressurization events are rare but can occur when mains break or electrical power is lost. When an event occurs, it is strongly recommended to issue a boil alert to those affected. Public water systems can issue a boil alert without consulting Ohio EPA, but boil alerts that affect a major portion of the distribution system must be reported within 24 hours. The municipality may lift voluntary boil alerts after the system is pressurized and the designated operator clears the system for providing drinking water. (Editor's Note: Please see your state agency for reporting requirements that affect you.)

The best way to avoid a depressurization is to keep the water and power flowing. When all power is lost through the electrical grid an alternate source of energy that will run the treatment plant and the distribution system critical components, such as a generator, is an excellent choice. 

Water main breaks are resolved by isolating the break quickly while maintaining water pressure to the rest of the system. This approach works well when all valves are accurately identified and working properly. A valve exercising program identifies the valves and keeps them working correctly in case they are needed. 

Water Age
The issues related to water age are directly attributable to water quantity and quality needs. These vital needs are always in conflict because quantity objectives dictate excessive storage issues while quality strives to minimize storage time while maintaining appropriate disinfectant residuals. Public water systems must strike a balance to minimize water age, effectively limit the formation of disinfection by products (DBPs) such as HAA5s and TTHMs, and keep disinfectant residuals within regulatory limits. 

A Distribution System Optimization Plan (DSOP) offers a mix of options for public water systems to meet quantity and quality standards by optimizing treatment and storage capabilities. OAC Rule 3745-81-78 (Note: This is now a rescinded Ohio regulation.) details the DSOP requirements and options. For more on sanitary surveys for small water systems, read Preparing for a Sanitary Survey for Small Public Water Systems.

Tribal Utility News Subscribers Give Us Insight into Tribal System Needs

When we launched our Tribal Utility News newsletter in 2012, we asked new subscribers about the challenges and education needs they felt were unique to tribal utilities. We got about 60 anonymous responses. Our subscribers include tribal operators, various technical assistance providers, and staff from several agencies that serve tribal interests. Judging from the responses we received, all three of these groups appear to be represented in our survey results.

My Problems Are Your Problems

While there are unique challenges facing tribal utilities, some of the common themes from the survey results address challenges faced by small utilities all over the country. Many small systems struggle to find and keep certified operators, raise the money to keep the system going, and keep the board engaged with the utility’s needs and responsibilities. While the specific ways in which those challenges crop up may be specific to tribes, a lot of resources intended for small rural systems could be helpful to tribal utilities as well.

Tribal Challenges

That said, tribal systems also face unique challenges related to sovereignty, government, federal support, and tribal issues and attitudes.

Remoteness and Isolation
Survey respondents mentioned that some tribal systems may not recognize that there are opportunities to cooperate or reach compromises with nearby non-tribal systems. In some cases, non-tribal water utilities might provide support that’s more conveniently located than tribe-specific assistance providers in the region. On the flip side, some tribes are in such secluded areas that they may be inaccessible to state and county support. And some tribes may wish to work with state entities but be facing other roadblocks.

Support From Tribal Government
As with many small rural utilities, tribal utilities sometimes struggle to get meaningful support from those in charge. Sometimes the tribal government doesn’t understand the need for qualified operators to run the system. Sometimes the tribal council doesn’t want to get involved in the utility at all, or ends up using utility job appointments for political patronage. Sometimes there just isn’t interest in water and wastewater issues.

One possible solution to these challenges was mentioned by a few survey respondents: utility boards. For most tribes, the water utility is under the direct control of the tribal council. Creating a separate water board allows the tribal council to focus on other governance issues while still ensuring that the utility receives guidance and oversight.

Dependence on Federal Entities
Some tribes don’t want to take ownership of their utilities, preferring to rely on federal support. Other tribes may want to be engaged, but find themselves dependent on slow-moving federal bureaucracy and assistance.

Tribal Issues and Attitudes
A number of factors related to the broader culture and conditions on the reservation could affect the performance of a tribal utility. Reservations with high unemployment might see their newly trained operators leave the utility for a better-paying job elsewhere. Sometimes there is resistance to working with non-tribal systems or working with outside entities to deal with problems or repairs. Some tribes may have restrictions in place that make it difficult for non-tribal operators to find someplace to live on the reservation. And finally, as with any small community, sometimes tribal politics affect the utility’s operation and management.

Tribal Education Needs and Resources Follow From These Challenges

As might be expected, most of the education needs highlighted by our survey respondents were in response to the challenges they mentioned. Basic management and operations topics topped the list. Luckily, while there are many challenges facing tribal utilities, there are resources available to meet those challenges.

Management Training a Must
The management support topics mentioned in our survey response covered the full range from record-keeping, ordinances, enforcement, and asset management to rate-setting, budgeting, and funding sources. This is probably related to respondents who felt that tribal councils didn’t always fully support the tribe’s utilities. However, there has also been increasing awareness that managerial support is a need for many small systems. Managing a utility in a small community can present special challenges. Finding funding can be more difficult, particularly for tribes. And things like enforcing ordinances or collecting past-due fees can be awkward when you know all of your customers personally. But when the utility managers feel able to tackle these challenges, the whole utility is able to provide better service to the community and a better work environment to its operators. 

For tribal councils and utility managers who want to learn more about the work that goes into managing a small utility, the Rural Community Assistance Partnership (RCAP) has several useful guides for boards. You can also browse the guidebooks collected by RCAP regional affiliate RCAC. For utility management advice and certification from a tribal perspective, check out the Tribal Utility Governance Program Training Manual and the Inter Tribal Council of Arizona's Tribal Utility Management Certification. Or check our calendar and document database for events and resources relevant to tribal managers.

Tribal Operators Make the Whole Thing Go
For operators, survey respondents focused on general O&M education topics like SCADA, safety, and general mechanical training. Water and wastewater treatment and distribution topics were mentioned, but much less frequently. Many small rural utilities have difficulty keeping trained operators on staff. The isolation and other challenges faced by tribal utilities often exacerbate this problem. This means many utilities have to periodically start from scratch, introducing apprentice operators to the basics of operation and maintenance. Luckily, there are a growing number of resources for tribal operators, in addition to the general operations training available in all states. The Inter Tribal Council of Arizona (ITCA) and the United South and Eastern Tribes (USET) both have federally-recognized tribal operator certification programs. ITCA, the Navajo Nation EPA, and the Native American Water Masters Association (NAWMA) all offer free training for tribal operators, and USET hosts an annual operator summit. And of course, searching our calendar for the Tribal category tag or under State for the National Tribal Operator Program will bring up even more trainings for both tribal operators and tribal utility managers, covering topics from grant-writing and GIS to general O&M and drinking water treatment standards. 

On a related note, a few survey respondents mentioned a need for awareness about certification programs for operators. Because clean drinking water and the sanitary disposal of waste are so essential to public health, it benefits communities to have operators who have received the proper training to achieve these goals. It can be easy to get bogged down in the day-to-day issues of running a utility, but ultimately, the role that utilities play in public health is their most essential service to the community. Operator certification programs are a way of ensuring that operators have received sufficient training to preserve public health. And well-trained, competent utility management helps ensure that those trained operators have the resources they need to do their jobs.

Help is Out There

Guidance manuals and standard operator trainings are all well enough, but sometimes a utility faces a situation so seemingly insurmountable that help is needed. Major problems with infrastructure and complex operations, budgeting, and management challenges often call for outside experts to help utilities find their way. Tribal utilities have these resources available to them as well. Our tribal contact manager is designed to help you determine which assistance providers are available in your area. In addition to federal resources like the Indian Health Service and USEPA regional offices, most RCAP regional partners and state based technical assistance providers may be able to assist you. (Some RCAP partners have staff specifically for tribes as well.) Regional tribal associations with utility management and operations resources like those mentioned above generally offer technical assistance as well. To see our full list of Tribal Assistance Providers, go here. For an overview of our tribal resources at WaterOperator.Org, see this video. Even if you don’t need a hands-on technical assistance provider right now, it might be a good idea to figure out who your best contacts are, so you can be prepared for life’s little surprises.

You're Not Alone

Tribal utilities face many unique challenges, but that doesn’t mean that leading or working for a tribal utility is impossible. There are education, technical assistance, and financial resources available to tribal utilities that need help, and practical solutions to even the most unique problems. We’ll be sharing some of those resources here on the blog, and the technical assistance providers we mentioned above will probably know about even more. To keep up with the latest tribal news and resources we’ve collected, subscribe to our newsletter, and let us know if there are more resources, challenges, or tips we need to know about as we work to serve tribal utilities in the future. 

Tribal Resources from and USEPA

At we recognize that small tribally-owned and operated public water systems often face unique challenges, beyond what impacts other small and rural communities. Because of this, we have created a number of ways to find information that is specific to tribes. This video provides an overview of our document and event databases, tribal newsletter, tribal assistance provider list, and the tribal contact manager.

For a sampling of documents we’ve collected in our document database, here are some of the USEPA documents we’ve found are particularly relevant for tribes.

For tribal drinking water systems:

For tribal wastewater systems:

And for tribes concerned about protecting their source water:

Check out the video for more on the resources we collect and offer, and if there’s a tribal resource you think we really need to know about, tell us in the comments!

Common Treatment Deficiencies

This article was first published in the Summer 2012 issue of Spigot News, the Ohio EPA's drinking water program newsletter. Many thanks for allowing us to republish it! You may also be interested in the article Common Source Water Deficiencies.

Ohio EPA conducts sanitary surveys at least once every three years at community public water systems (PWS) and once every five years at non-community PWSs. The purpose of a sanitary survey is to evaluate and document the capability of a water system’s source, treatment, storage, distribution, operation and maintenance, and management. Each of these may favorably or adversely impact the ability of the system to reliably produce and distribute water that meets drinking water standards. 

This article is the second installment in a series of articles to help small water systems identify the most common problems found during a sanitary survey or other investigatory site visit conducted by Ohio EPA staff. The first article focused on source water (well) deficiencies. This article will focus on some of the more common treatment equipment deficiencies which are found during inspections of small water systems.  Future articles in this series will cover distribution deficiencies and other topics. 

Backwash discharge lines: If you have a softener or a pressure filter, you backwash your equipment to clean and replenish the media. The waste that is produced when you backwash discharges into a floor drain or another pipe, which carries the waste to where it will be treated.  If the pipe carrying the backwash wastewater from your treatment equipment is too close to, or even inserted into, the drain or pipe that carries the waste to treatment (see Figure 1), you could end up with back-siphonage.

This could occur if the pipe carrying the waste to treatment backs up and the wastewater is siphoned back into your drinking water treatment equipment, contaminating your treatment equipment with whatever waste the pipe is carrying. Solution: Ensure there is a sufficient air gap between the backwash waste pipe and the floor drain or the pipe conveying the waste to treatment to prevent backsiphonage (see Figure 2). 

Softener tanks, cover, and salt: Softener brine tanks should be kept in sanitary condition. The brine solution should be kept free of dirt and insects. Solution: The best way to accomplish this is to completely cover the brine tanks with an appropriately fitting lid. The lid should not be over- or under-sized and should be kept in place on top of the tank. Also, the brine tank should not be overfilled such that the lid does not fit snug on the tank (see Figure 3).

All substances, including salt, added to the drinking water in a public water system must conform to standards of the “American National Standards Institute/National Sanitation Foundation” (ANSI/NSF).  This is to ensure it is a quality product that will not introduce contaminants into the drinking water. Solution: Ensure the ANSI or NSF symbol can be located on the bags of salt you use or ensure your salt supplier can provide you with documentation from the salt manufacturer that it is ANSI or NSF certified. 

Cartridge filters: Over time, cartridge filters will become clogged with iron or other minerals from your source water. When clogged, the filters become a breeding ground for bacteria. Solution: Ensure filters are replaced in accordance with the manufacturers’ specifications or even more often, depending on the quality of your source water.

General maintenance:
 Water treatment equipment should be accessible and cleaning solutions and other non-drinking water chemicals and materials should be kept away from the equipment. If treatment equipment is not accessible for Ohio EPA staff to inspect during a sanitary survey, it will not be accessible to the water treatment operator for routine maintenance or during an emergency. Likewise, non-drinking water chemicals stored in close proximity to treatment equipment can be an invitation for a mix-up or, even worse, intentional vandalism (see Figure 4). Solution: Keep clutter and non-drinking water chemicals and equipment away from drinking water treatment equipment. Preferably, these items should be stored in a different room.

Developing A Better Understanding of Drinking Water Technology Approval: WINSSS Center Project B1

When EPA in 2014 chose to fund the National Centers for Innovation in Small Drinking Water Systems, their vision for the Centers was much more than developing new drinking water technologies; they asked them to also consider facilitating acceptance of both new and existing technologies, improving relationships between stakeholders, fostering dialogue among regulators, and facilitating the development of uniform data collection approaches for new technologies. All of the non-treatment pieces of the vision have been incorporated into the WINSSS Center’s Project B1.

Project B1 has three objectives:

  1. Conduct a survey of the states to determine the barriers and data needs for technology acceptance.
  2. Develop a states workgroup and use the survey results as a starting point to discuss how to overcome those barriers and develop a set of uniform data needs.
  3. Take the workgroup results and apply them to the New England states to work toward multi-state acceptance.

The first objective has been completed, and the workgroup called for in the second has been meeting every other month since December.

Recognizing the importance of state buy-in to the project, the PI’s proposed to include the Association of State Drinking Water Administrators (ASDWA) as a partner in the survey implementation at the proposal stage. They have been a great partner, and the success of this project is a reflection of their involvement. It was also clear early on  that both Centers had proposed work related to developing a better understanding of acceptance of technologies, so we joined forces. It proved instrumental in the development of the questions, and there were at least eight participants from WINSSS, ASDWA, and DeRISK, that had a hand in the question development.

The survey included 16 questions asking states about their approach to technology acceptance, their experiences with new technologies, barriers to getting these technologies to small systems, data needs for acceptance of any new technology, and their interest in participating in our effort. Forty  states responded, again thanks to ASDWA’s involvement, and the data were telling. We learned that many states don’t consider new technologies for small systems because of cost and risk and that states generally struggle with having the staff and technical expertise to understand and approve new technologies. The most common barriers were a lack of staff and staff time to approve technologies, adequate performance data from vendors, funding for testing/evaluation, and training for state staff.

We asked the states to tell us what questions they needed answered to approve a technology, and over half of the states listed performance data to support the technology, pilot data from multiple locations or water qualities, residuals produced, third party certification and understanding of where technology is appropriate, and understanding the operator skills needed to operate the technology. They also listed the data deficiencies they see most often. These included range of water qualities tested, length of pilot testing, scale of pilot testing, and operating costs, among others.

The good news is that 11 of 14 “emerging” technologies provided to the states in the survey have already been implemented in at least 10 states. This suggests that more technologies are in use than we initially believed and for some technologies, better sharing and communication mechanisms between states are the most immediate needs.

We also asked states how they used the data from EPA’s Environmental Technology Verification Program (ETV) and Arsenic Demonstration Program in accepting new technologies. Nineteen states said they rely on ETV certification or testing protocols as part of their process. Fifteen states said that the Arsenic Demo Program influenced their decisions related to the tested technologies. These programs no longer exist, but they provide valuable insight into how we might consider developing a new program to support the states for sharing data and communicating technology approval information.

The last part of the survey focused on technology acceptance and asked the states if they would be interested in sharing data, developing common standards with neighboring states, or partnering with nearby states to coordinate technology approval. Six states did not answer this question, but 33 of the 34 who did were at least somewhat interested in developing a data sharing network. Twenty-eight states were also interested in developing common standards with nearby states, and 23 were interested in developing partnerships with nearby states to approve technologies. These are very encouraging results.

The survey data were shared with the states, and a workgroup of Centers, ASDWA, and state staffs was formed. The first meeting was in December 2015, and much progress has been made since. The workgroup has developed a draft framework for an entity that would support a shared data repository. They are currently developing a plan/proposal to share with the Interstate Technology & Regulatory Council board (ITRC) to consider how this entity might work with or within the existing ITRC framework. No decisions on this have been made and the workgroup is evaluating options. An open call to all industry stakeholders is planned for late July or early August to share progress to date and to get feedback.

There are no illusions that this can all be accomplished in a short time; the issues and barriers related to technology acceptance have been discussed within the industry for more than 25 years. But this project has created buzz within the industry, as well as with the states and USEPA. It has momentum, and the idea of developing a consensus approach for sharing data and fostering cooperation among all stakeholders that both supports the states need to protect public health and makes it easier for technologies to be accepted by states is now being discussed among all of the relevant players.

Common Source Water Deficiencies

This article was first published in the Winter 2011 issue of Spigot News, the Ohio EPA's drinking water program newsletter. Many thanks for allowing us to republish it!

Ohio EPA conducts sanitary surveys once every three years at community public water systems (PWSs) and once every five years at noncommunity PWSs. The purpose of a sanitary survey is to evaluate and document the capability of a water system’s source, treatment, storage, distribution, operation and maintenance, and management; these all may adversely impact the ability of the system to reliably produce and distribute water that meets drinking water standards.  

This article covers the sanitary survey or other investigatory site visits conducted at the water source and concentrates on the most common deficiencies found during the visit of small PWSs. Even though the article focuses on small systems, similar deficiencies can be found at larger public water systems. Future articles will cover treatment, distribution and other topics. 

There are common deficiencies surveyors hope not to find when conducting a sanitary survey, or when following up on complaint investigations or responding to total coliform bacteria positive sample results. Figures 1 and 2 show poor water sources and figure 3 shows an acceptable water source. Figure 1 shows a well equipped with a sanitary seal which is missing bolts. It also shows that the casing is flush or in line with the finished grade, and the electrical wire and raw water line are exposed and unprotected. Although the well is vented, it does not have a screened vent. The well is also not protected from surface water runoff, other contaminants or critters. 

Figure 2 shows a public water system well located in a parking lot. The well cap is missing bolts and therefore is not properly secured to the top of the well casing. There is also a depression surrounding the casing. If rainwater pools near the well, it can seep down along the casing and negatively impact the ground water and its quality. Located to the left of the well are bags of sodium chloride, which increases the potential for rust at the base of the well. Also, there is not enough protection around the well to prevent damage from motorized vehicles to the casing or electrical conduit.  

Although you can’t see this in the picture, the well has a 1988 approved “National Sanitation Foundation” (NSF) well cap but it is not a “Water System Council” PAS-97 (or Pitless Adapter Standard, 1997) approved cap as required. The PAS-97 cap provides a properly screened vent which is not present in this cap. 

Figure 3 shows an acceptable water source. The well casing extends approximately 24 inches above finished grade, which is beyond what is required (at least 12 inches above finished grade). The finished grade is sloped to drain surface water away from the well.  The approved well cap fits flush over the top of the casing and electrical conduit; it provides a tight seal against the casing and prevents the entrance of water, dirt, animals, insects or other foreign matter. The well is also properly protected with concrete filled posts to protect it from motorized vehicles and mowers. 

Educate Decision Makers With Help From RCAP

Google “drinking water” or “wastewater,” and you’re sure to find a growing list of news articles about lead safety concerns, the recent PFOA and PFOS advisory, nitrogen and phosphorus pollution, and our crumbling infrastructure. The weight and fervor of these public discussions may concern some who grapple to protect our drinking water and environment. But increased attention has its benefits. It could mean your board members and other community decision makers would be more receptive to learning about your operations and operational needs. And that’s an opportunity you don’t want to miss.

Last year, the Rural Community Assistance Partnership released two video series designed to help leaders in small, rural communities make more informed decisions about drinking water and wastewater operations, maintenance, and expansion. Each video spends roughly 2-4 minutes walking the audience through a different technical step in the drinking water or wastewater treatment process. Click on the links below to watch the videos.

Wastewater Treatment

  1. Introduction
  2. Collection system
  3. Preliminary treatment
  4. Primary treatment
  5. Secondary treatment
  6. Solids and sludge handling
  7. Effluent disinfection
  8. Effluent disposal

Drinking Water Systems

  1. Introduction
  2. Raw water intake
  3. Pre-settlement and pre-treatment
  4. Static mixers and flash chambers
  5. Sedimentation and filtration
  6. Distribution systems

Beyond these series, sharing the RCAP video The Importance of an Operator in a Community’s Water System with your governing body will provide insight into the day-to-day work of an operator and the importance of that role.  

Click here to browse these videos in a playlist.

To find more videos from RCAP and other technical assistance providers, visit our Documents Database and click Videos in the Type category. And subscribe to the newsletter to get featured videos and other resources sent straight to your inbox.  

Tools for Transient Public Water Systems

Does your truck stop, restaurant, or campsite supply water to customers from a well or other privately-owned water source? If so, you’re what I.S. EPA calls a transient noncommunity public water system. And you’re not alone.  Every business and organization across the country that serves at least 25 people—not necessarily the same people—for at least 60 days out of the year is a TNC and must comply with Safe Drinking Water Act regulations and any requirements set by the local primacy agency. 

Getting and staying in compliance can be complicated, but your state’s primacy agency and your local technical assistance providers are there to help. If you aren’t able to confidently answer any of the questions below, you should consider reaching out for guidance to ensure you are providing safe water.

  • Is your system’s water source approved for public consumption?
  • Are you required to have a licensed operator?
  • Do you know what chemicals you’re required to sample and how frequently?
  • Are you up-to-date on your sampling requirements?
  • Do you know what type of treatment is best for your source water?
  • Do your tanks, pipes, and pumps align with state capacity and flow rate rules?
  • Do you have—and are following—an operations and maintenance plan that aligns with state and federal requirements?
  • Are all other required manuals and plans up-to-date and stored in a safe location? This may include engineering plans and maps, an emergency response plan, and evidence of compliance with EPA risk management requirements.
  • Do you have an organized record of all operation and maintenance activities?

You can also find more information on many of these and other small system concerns through our documents database. This short video tutorial can help you get started. 

Starting Off on the Right Foot: Basic Seasonal System Startup

As summer draws near a lot of small, seasonal water system operators are showing up, blowing off the cobwebs, and getting the show on the road. Every state has slightly different regulations and requirements for small system startup, and it’s important to know what your state requires. The Revised Total Coliform Rule requires seasonal systems to certify that they've completed state-approved startup and sampling procedures, so be sure to check anything we say here against your state's guidance. Having said that, it doesn't hurt to have a few reminders as you work through your startup routine. Here, we summarize the most common considerations for small seasonal system startup.


The first thing you need to do is inspect your system. Even if everything was ship-shape when you closed your system down, life has happened while you were away. There could be storm damage, animals could have gotten into your well house or your well, or Murphy’s Law could have paid your system a visit. Each system is slightly different and will need to be checked for slightly different things. The Connecticut Department of Public Health has a great guidance document with detailed instructions for inspecting and repairing drilled wells with the wellhead at the surface or in a pit, old dug wells, and well houses or pump houses.

Regardless of your well construction, here are a few basic inspection tips to keep in mind:

  1. Clear the area around your well head. Remove trash, brush, debris, and any other potential sources of contamination to at least the recommended setback distance around your well. Make sure to store chemicals (including pesticides, fertilizer, gasoline, etc.) in another location away from your wellhead. If you have a generator, make sure that it has backup containment for possible fuel spills. Make sure the ground is sloped so that water can’t puddle up around your well.
  2. Remove any animals from inside the well, including bugs and spiders, which can introduce bacteria to the well. Bugs and spiders can be removed with a shop vac. Replace the sanitary seal or repair the dug well cover so that animals cannot enter the well.
  3. Any system component that has a vent should also have a secure vent screen, and the vent opening should point downward. Make sure the vents are clear and unobstructed.
  4. Check your wiring, conduits, and electrical systems to make sure that they’re in good shape. This is important with any form of well construction, but pay particular attention in a well house or pump house, as rodents like to live in these structures and may damage your wiring. If there are rodents living in your well house, be sure to clear them out.
  5. If you have a chlorinator, properly dispose of your old chlorine and purchase new. Make sure that your chlorine residual test kit is working properly, is properly calibrated, and the reagents are not expired. Inspect the chlorinator itself to make sure that it is in working order.
  6. Storage and pressure tanks will need to be drained, any sediment removed, and disinfected. Storage tanks may need to be re-lined or otherwise repaired before they can be used. This is particularly true if they have never been serviced before. These repairs are best done by a professional. If you choose to re-line a tank yourself, make sure to have proper safety and ventilation equipment in place before you begin.

Turn it on

Once you’ve gotten a good look at your system and done any preliminary repairs, it’s time to turn it on. Different states will have different requirements on what samples and readings need to be taken during this process; be sure you know what’s required where you’re working. Run water through the system by opening hydrants, blow-offs, and faucets. Check that your pressure tank is maintaining correct pressure and the pressure relief valve is working properly. Check the pressure throughout your system. Walk your distribution lines to make sure they are not exposed or leaking. (Leaking distribution pipes, in addition to wasting water, can also let bacteria into your system.) Chlorinate the system (we like this guide) and let it sit overnight or 24 hours. If your system has a water softener, high chlorine levels can damage the resin, so bypass the softener and disinfect it separately according to manufacturer instructions. Don't let anyone use the water during this time, both so that the chlorine has enough time to disinfect the pipes, and so that your users are not harmed by the highly chlorinated water.


Once the chlorine has had a good long time to work on the bacteria that grew while you were away, flush the highly chlorinated water out of your system. Don’t flush the water into the septic system. This will kill the good bacteria that help the septic system work. Also try to avoid vegetation and surface water that could be damaged by the chlorine.


This is the point where the Revised Total Coliform Rule sampling kicks in. Be sure to refer to your state's sampling requirements and your sample site plan in order to keep your system in compliance. Wait until you have the lab results back and have confirmed the water is safe to drink before you allow anyone to use the system for drinking water. If you chlorinate, this is also a good time to check that you have the correct chlorine residual in your system, and to adjust the chlorine feed if necessary.

If you’re concerned that your system may need additional water quality tests, don’t be afraid to request them! It’s always good to know what you’re dealing with.

Put your house in order

Though these are the basic steps to getting your system up and running, there is more that goes into running a seasonal system.

Valve exercising is an important part of distribution maintenance for any system. Take some time to systematically turn the valves in your system on and off as you’re bringing it online. Then you’ll know they’re working if an emergency comes up later in the season.

Backflow prevention is just as important in a small system as in a big one. Make sure your hose bibs all have vacuum breakers installed. If your system has RV sewer dump stations, make sure they’re isolated from the drinking water system by backflow assemblies (or that the water lines don’t reach the stations at all). Have a professional inspect any testable backflow assemblies you have on your system.

As you go through the process of starting up your system for the season, take some time to make sure your manuals and emergency contacts are up-to-date, your instruments are properly calibrated, and your chemicals are all up-to-date and properly stored. Taking some time to put your (well) house in order at the beginning of the season gives you a great starting point for the coming months of small system operation.

Good luck, and don’t forget to lock your pump house!