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WaterOperator.org Blog

Articles in support of small community water and wastewater operators.

Featured Video: How To: Develop a Cross-Connection Control Plan

Featured Video: How To: Develop a Cross-Connection Control Plan

A well-developed cross connection control plan ensures that backflow events are an infrequent occurrence in drinking water distribution systems. Cross connections involve any connection between treated water and untreated water. The connection can allow for backflow and ultimately drinking water contamination.  You can learn about the two types of backflow, backpressure and backsiphonage, as well as how they occur in RCAP’s 2018 blog on Cross Connection and Backflow Prevention – Underutilized Protection for Potable Water. Additionally, WaterOperator.org has featured two backflow videos in a previous blog that will help you learn more about the phenomenon.

To prevent unnecessary contamination in your distribution system this week’s blog post features an RCAP video on how to develop a cross connection control plan. This short video describes the key administrative and technical provisions that should be included in your plan. We’ve also highlighted some useful resources that can help you follow their suggestions. If you'd like to find state or territory specific resources such as a sample ordinance or cross connection control plan template, visit our document library 

 

Now that you know the key provisions to a successful backflow prevention program, check out these additional resources. Remember that many state or tribal territories can have their own rules and specifications that need to be met by your utility. Consults with your system's primacy agency before starting or updating a cross connection control program.

Backflow Prevention – Idaho Rural Water Association
This 2-sided brochure can be used to educate your customers about potential sources of backflow and the impacts of contamination.

Residential Cross-Connection Questionnaire – Alliance of Indiana Rural Water
This 2-page questionnaire can be set to customers to identify potential sources of cross connection.

Selling Cross-Connection Control to Management- University of Florida Center for Training, Research, and Education for Environmental Outcomes
This power point, presented by Ron Chapman, describes how you can encourage your utility to implement a cross connection control program.

Cross-Connection Control Manual – U.S. Environmental Protection Agency
This manual has been designed as a tool for health officials, waterworks personnel, and plumbers to understand the basics about backflow prevention, preventer testing, and control programs.

Featured Videos: Backflow Prevention & Cross Connection Control from AWWA

Featured Videos: Backflow Prevention & Cross Connection Control from AWWA
No one wants to experience a backflow incident. Depending on what contaminant was involved and how much of the distribution system was affected, these incidents range from being a lot of work and expense to being a full-blown public health crisis. (See the bottom of this page to browse real backflow incidents that have occurred here in the U.S. as well as Australia and Canada.) Either way, a lot of people will have their water service disrupted and you'll have a lot of extra work on your hands until the situation is resolved.

If you're hoping to prevent a backflow incident in your community, this week's videos, courtesy of AWWA, could help. The first video explains the basics of backflow and backsiphonage and provides a brief overview air gaps and backflow prevention assemblies. The second video covers similar topics but goes more in-depth on backflow prevention assemblies, discussing the most common models, how they work, and where and how they should be installed. The first video is about 5 minutes and the second is about 7-and-a-half. 




If you'd like more training on backflow and cross connection topics, visit our event calendar and select the Backflow category and your state. If you'd like to do more reading on your own, visit our document database and select the Backflow category and the Manuals/Handbooks document type.

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. 

Cross-connection
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 8745-81-78 (Note: This is for regulated entities in Ohio.) 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.