Can A Septic Tank Float?

As crazy as it might sound, the answer is yes: Septic tanks can float out of the ground. Any buried structure will float when empty if it weighs less than the water that displaces it. That means that when installing any sort of septic system in an area with a high water table and/or that is prone to flooding, you must conduct buoyancy tests and determine if the system will remain stable.

Dr. Sara Heger, instructor at the University of Minnesota’s Onsite Sewage Treatment Program, has broken down the calculation to determine tank stability at Onsite Installer. The basic steps are below, but Dr. Heger’s walk-through explains each step in detail and shows example calculations. You will need to know the individual weights of the following: the empty tank, the minimum amount of water and media in the tank, the soil directly above the tank, and the maximum volume of water that is displaced.

Here’s the calculation:

1. Calculate the weight of water displaced by the tank (buoyant force B).
2. Calculate or look up the weight of the tank (WT).
3. Calculate the weight of the water in the tank (WW).
4. Calculate the weight of the soil cover (WS).
5. Evaluation of net forces.

So if your calculations indicate that the tank will float, what do you do then? Thankfully, there are anti-floatation measures that can be added to the system design plans. Perhaps the most basic is to use concrete, which weighs 85 pounds per cubic foot and can be added into the design in a few different ways. Some fiberglass tanks may also have an anti-floatation lip built onto them.

It’s important to consider that any anti-floatation measure will increase stress forces on the tank, so the tanks must be able to withstand the extra force. Read more from Dr. Heger at Onsite Installer on anti-floatation.

If you ever do need to deal with a flooded septic system, whether the tank has emerged from the ground or not, refer here:

• “Faced with a Flooded Septic System?” also from Dr. Heger at Onsite Installer
• “Protecting a Septic System During and After a Flood” at WaterOperator.org
• Contact the Onsite Sewage Treatment Program at UMinn.

Medications & Your Septic System

Can taking some forms of medications harm a septic system? The short answer? Yes. Some chemicals from medications are not completely metabolized in your body and are expelled in your waste. These chemicals can disrupt the biological action in your tank and drainfield causing it to fill with solids more quickly. More solids in your tank means there is a higher risk of solids flowing into the drainfield leading to septic system failure. 

The best way to ensure your septic system stays healthy and functioning is to provide consistent maintenance and inspections. It is also very important not to flush any medications or household chemicals (antibacterial soaps, harsh cleaning chemicals, chlorine bleach, etc.) down your toilet or sinks. Septic tanks and drain fields depend on both anaerobic and aerobic bacteria to break down the organic waste and clean the water as it is released it into the soil for filtration.

Some steps to protect a costly failure and potential replacement are:

• Flush only body waste and toilet paper down the toilet
• Use minimal household chemicals for cleaning
• Avoid or use minimal amounts of chlorine bleach in your washing machine
• Have your tank pumped more frequently if someone in your household is taking chemotherapy or antibiotic medications for an extended period
• When your tank is pumped, ask your pumper to refill it with fresh water to dilute any residual medications
• Take excess and unwanted chemicals, cleaners, and medications to your local household hazardous waste or medication collection program

Businesses on Septic Systems

If a business is in an area that does not have a public sewer system, or, if the business will generate a higher flow of additional wastewater than a sewer system will be able to handle, a commercial septic system will be necessary. This type of system, also called a large-capacity septic system, is defined by the U.S. Environmental Protection Agency as "a septic system that receives solely sanitary waste from either multiple dwellings or a non-residential establishment that has the capacity to serve 20 or more people per day."

The wide variety of facility types that a large-capacity system could service include schools, religious institutions, office and commercial buildings, shopping malls, hotels, restaurants, convenience stores, and more. Unlike residential septic systems or non-residential systems serving fewer than 20 people per day, the EPA does regulate large-capacity systems in order to protect underground drinking water sources.

Fundamentally, though, a septic system on a business property works in much the same way as a residential system, just on a larger scale. To keep up with the higher volume of wastewater the system will be handling, large systems will require more frequent pumping, maintenance, and service to ensure they operate properly for as long as possible. Business owners managing water use so that the system is not overwhelmed will also help keep the system in good working order.

Again, similarly to residential systems but on a larger scale, the costs of both installation and operating large-capacity systems will vary widely based on the individual factors of the commercial location and performance needs for the system.  

There are some differences to keep in mind for large-capacity systems. While these systems still only handle sanitary waste (so no industrial waste allowed), there are still different types of wastes produced by commercial buildings that their large-capacity septic systems will need to be able to handle. So they’ll need additional design components — such as grease traps in restaurants to keep fats, oils, and greases (the notorious FOG!) from clogging up the plumbing — and more specialized maintenance and service.

Multiple types of septic systems can be used for a commercial installation. AAA Pumping Service recommends sand filter systems, pressure distribution systems, evapotranspiration absorption systems, and cluster systems as well-suited for commercial properties. (A cluster system would serve multiple nearby businesses/commercial properties).

Note: Mention of commercial entities who share educational information does not constitute an endorsement.

Additional Reading

• Large-Capacity Septic Systems | U.S. EPA
• Best Septic Systems for Your Commercial Property | AAA Pumping Service
• Five Facts About Commercial Septic Systems | Moon Site & Septic
• Five Things to Know About Commercial Septic Systems | World Construction Today
• “Design Concerns with Restaurants, Convenience Stores, and Commercial Waste” Presentation | Onsite Installer

Protecting a Septic System During and After a Flood

When a home or the area surrounding it floods, the septic system is at risk of becoming waterlogged. This could be from a leak in the lid, rising groundwater that enters into the system, or an over-saturated drainfield that can't properly drain. A flooded septic system may lead to sewage backing up into the home and cause serious problems for the homeowner. 

Septic tanks may not always experience damage just because there is flooding, but any existing leaks in the system will allow floodwater, silt, and debris to enter the system. This presents a big problem since the extra dirt and debris can cause clogging. Extra water entering the septic system can also cause the floating solids to rise up and plug the pipes. The U.S. Environmental Protection Agency has information on what to do after a flood to ensure your septic system is protected. Below we have summarized this information with a list of dos & don'ts:

Septic System Flooding Dos & Dont's

This video provides some additional tips for how to avoid septic tank flooding and what to do if your system does flood:

Following these tips will help septic system homeowners to be prepared in the event of a flood and protect the septic system from further damages. If you need more specific advice or assistance with your septic system, contact your local health department for a list of septic system contractors in your area.

Surprising Facts About Septic Systems

Septic systems treat and dispose of wastewater for locations that public wastewater systems do not service. Many homeowners living with a septic system don't know much about it other than the fact that they have one. If more homeowners learned the ins and outs of their septic systems, they would have the ability to prevent issues before they arise. This article from Dano's Septic (excerpted below) reveals some surprising facts about septic systems.

Every home has a different pumping schedule

• Septic systems must be maintained regularly (at least once every 3-5 years) but the exact frequency depends on some factors like tank size, system age, and usage habits.

You can't flush everything

• Flushing items like pet waste, feminine products, and even floss can interfere with the system's ability to break down waste and create the need for premature pumping of the system.

Drain cleaners can be dangerous

• Chemical drain cleaners can mess with the balance of your septic tank and create problems down the road. Avoid this "quick fix" whenever possible and call a professional to help unclog any drains.

The system involves much more than just the toilet and tank

• Every single sink, tub, and pipe in the home is connected to the septic system. Even the garbage disposal can affect how the system functions, so it is important to pay close attention not only to what is being flushed down the toilet, but also what is poured down the drain.

Your system can affect the groundwater

• Septic systems have the potential to contaminate the groundwater since whatever enters the septic tank will eventually reach the drain field and seep into the ground.

Drain fields can flood

• This is one of the biggest concerns related to septic systems. When the drain field floods, it quickly contaminates the property with wastewater. Try to practice water conservation as often as possible and schedule a professional inspection annually to prevent this.

Maintaining your system will extend its lifespan

• Septic tanks can last for decades with consistent upkeep but eventually they will need to be replaced. Prioritize repairs and maintenance for the septic system to ensure the longest lifespan possible.

What Is a Cluster System?

According to U.S. EPA: "A cluster (or community) decentralized wastewater treatment system is under some form of common ownership and collects wastewater from two or more dwellings or buildings. It conveys the wastewater to a treatment and dispersal system located on a suitable site near the dwellings or buildings. It is common to find cluster systems in places like rural subdivisions."

Image from U.S. Environmental Protection Agency

Cluster systems transport wastewater from a small number of homes (typically 2-10) via alternative sewers to either a conventional treatment plant or to a pretreatment facility followed by soil absorption of the effluent. Cluster systems can be financially sound, environmentally friendly solutions for small community wastewater problems, where conventional central treatment systems are not practical or affordable and where individual onsite systems are inappropriate because of site or soil limitations. 

The advantages of cluster systems are the lower average cost, flexibility in land use, less complex operation and maintenance for the community, and non-discharging, decentralized wastewater treatment systems can provide an environmentally sound alternative for small or disadvantaged communities.

The main disadvantage of cluster systems is the amount of operation and maintenance needed. While it is typically not complicated, alternative sewers have septic tanks that need to be inspected and pumped and mechanical parts and controls that use electricity. Since cluster systems are located onsite, workers are required to travel to individual homes or businesses. This type of decentralized wastewater system requires more frequent maintenance, which can be costly if anything is malfunctioning. 

Another key thing to keep in mind is that cluster systems require a somewhat complex organizational structure in order to make community decisions like fee collection and continuing education of homeowners about wastewater issues. The cooperation of homeowners using the cluster system is much more important than with municipal systems since smaller systems are less resilient and less tolerant of periodic large flows or larger than normal loadings of household chemicals than in large systems, where these peaks are averaged out over a very large user base.

Developing a Septic System Owner's Guide

The Community Septic Owner's Guide online tool is designed to develop an Owner's Guide for everything from a single-family home, a commercial property, or even a cluster system serving 50+ homes. It was funded by the USDA National Institute of Food and Agriculture and created by the University of Minnesota. Some key things to keep in mind about this tool are:

• You will need to register if you are using the tool for the first time
• It contains generic stock/boiler plate general information, system component descriptions and images, and operations and maintenance (O&M) recommendations
• It allows you to upload site specific descriptions, images, and O&M recommendations
• It will produce a PDF guide for your home or structure to be used electronically or printed out
• It allows you to start and stop a project during the process and update it years later when things change
• It does NOT cover every scenario that exists across the US, but the creators of the tool hope it covers a vast majority of them

Onsite Wastewater Challenges | Onsite Overview #5

Using and maintaining decentralized wastewater treatment systems comes with its own unique challenges. Luckily, there are plenty of resources online that can assist in the troubleshooting process for any issues that arise. We have compiled a list of resources to get you started if you are interested in learning more about the challenges that accompany maintaining an onsite wastewater treatment system.

Our best resources on this topic:

Looking Back & Moving Forward | National Onsite Wastewater Recycling Association
This 29-slide presentation from NOWRA's 2022 Onsite Wastewater Mega-Conference provides a brief history of the application of decentralized onsite systems in rural America and highlights the challenges these legacy systems are currently facing. The presentation also details the water shortage challenges experienced across the country and highlights the need for better wastewater management to reduce the impact on our dwindling aquifers.

Using Nationwide and Local Data Sources to Address Decentralized Wastewater Infrastructure Challenges in the Contiguous U.S. and the Caribbean | U.S. Environmental Protection Agency
This 1-hour, 6-minute webinar recording explores solutions to data gaps on both national and local levels. In Puerto Rico, natural disasters including hurricanes, tropical storms, and earthquakes have accelerated the need to establish baseline information on septic systems. EPA, through the Caribbean Septic Systems Workgroup, is leading these efforts to assist state and local departments gather data to support planning and access funds to help residents.

Design Challenges with Liquid Effluent Collection | National Onsite Wastewater Recycling Association
This 21-page presentation from NOWRA's 2023 Onsite Wastewater Mega-Conference describes the advantages and disadvantages of using a Septic Tank Effluent Pump system (vs. a gravity system) for the transport of onsite wastewater to multiple tanks for disposal. 

Innovative Approaches to Address Decentralized Wastewater Infrastructure in the Alabama Black Belt | U.S. Environmental Protection Agency
This 2-hour, 2-minute webinar explores proposed solutions for the technological, regulatory, and management challenges of adequate decentralized wastewater management in the Black Belt, as well as progress made on current funding initiatives. The intended audiences for this webinar include decentralized and wastewater industry practitioners, engineers, public health agencies and practitioners, academia, government and municipalities, community and nonprofit organizations, and environmental justice advocates.

OSTDS Design & Install Challenges | National Onsite Wastewater Recycling Association
This 164-page presentation from NOWRA's 2023 Onsite Wastewater Mega-Conference focuses on Aerobic Treatment Unit (ATU) Onsite Sewage Treatment and Disposal Systems (OSTDS) and Subsurface Drip Irrigation (SDI) Drainfield, as well as Performance Based Treatment System (PBTS) OSTDS and Subsurface Drip Irrigation (SDI) Drainfield. The use of these systems is shown with examples of sites that are very small for the size of the home or business, increased wastewater flow, soil conditions or other conditions that are not suitable for a typical treatment system.

How to find more resources on this topic on our website?
If you are interested in looking through our database for the other resources on this topic follow the instructions below:

1. Select "CATEGORY" in the dropdown then choose "Decentralized WW Systems." 
2. Once you make that selection, a second dropdown will appear where you can choose "TYPE" if you are looking for a specific kind of resource (videos, factsheets, etc.)
3. Optional: In the Keyword Filter, you can type a specific word or phrase to target the search even further.
4. The last step is to click the "Retrieve Documents" button to see your results.  

Decentralized Wastewater on Tribal Lands | Onsite Overview #4

Tribal communities face unique challenges when it comes to the management of decentralized wastewater and it’s important that resources are developed with these specific challenges in mind. Simply having a septic system is not unique to those living in Indian Country, but many organizations have recognized that the basic resources available may not cover the questions that arise for tribes when it comes to the operation of these essential utilities. We have compiled a list of resources to get you started if you are interested in finding tribal specific information about septic systems.

Our best resources on this topic:
Water and Wastewater Utility Operation and Management for Tribes - Decentralized Wastewater Systems | U.S. Environmental Protection Agency
This 29-minute presentation includes such topics as system inspection, system maintenance, and "things to avoid" for septic tanks. The module provides an overview of decentralized wastewater treatment and processes and includes a special look at innovative decentralized technologies and "best practices" for managing onsite systems.

Helping Solve Wastewater Challenges in Indian Country | University of Minnesota Water Resources Center
This 56-page guide provides tribal community members and tribal wastewater professionals with a four-phase process on how to assess and find appropriate solutions to community wastewater issues in Indian country. It includes guidance on generating a Community Wastewater Assessment Report, types of septic systems, how to choose the most appropriate wastewater treatment system for your community, and how to implement these solutions. The process outlined here weaves in significant considerations specific to Indian country that will likely improve the success of wastewater projects.

A Homeowner's Guide to Septic Systems for Tribal Communities | U.S. Environmental Protection Agency
This 9-page guide, from the U.S. EPA’s SepticSmart! program, focuses on the unique factors of tribal communities and homeowners on tribal lands in caring for their systems. It contains tips for properly maintaining septic systems as well as troubleshooting for common failure causes.

Onsite Wastewater Management: A Manual for Tribes | New Mexico State University
This 80-page manual helps tribes to take steps to ensure that sources of drinking water are clean and adequately protected against contamination, and that wastewater is appropriately managed. Chapter topics include: Historical Perspective of Native American Wastewater Management, Soils and Site Inspection, Septic Systems, Passive Advanced Treatment Systems, Mechanical Systems, Disinfection, and Reuse and Conservation of Wastewater.

Using a Responsible Management Entity (RME) to Manage Tribal Onsite (Septic) Wastewater Treatment Systems | U.S. Environmental Protection Agency
This 4-page fact sheet/brochure describes the use of a centralized approach for the management of septic systems using a Responsible Management Entity (RME) for oversight and maintenance.

How to find more resources on this topic on our website?
If you are interested in looking through our database for other resources on this topic follow the instructions below:

1. Select "CATEGORY" in the dropdown then choose "Decentralized WW Systems." 
2. Once you make that selection, a second dropdown will appear where you can choose "TYPE" if you are looking for a specific kind of resource (videos, factsheets, etc.)
3. In the Keyword Filter, type “tribal” to make sure the resources are more targeted towards this topic.
4. The last step is to click the "Retrieve Documents" button to see your results.

How Septic Systems Work | Onsite Overview #3

Whether you are a septic system homeowner or an onsite wastewater professional, it is important to know all you can about the ins and outs of septic systems. Whether it be the basics of how they work, what types are available, or how to clean a septic tank, there’s no such thing as being overeducated when it comes to such an integral aspect of so many homes in the U.S. We have compiled a list of resources to get you started if you are interested in learning how to properly care for and maintain a septic system.

Our best resources on this topic:
About Septic Systems | Oregon Department of Environmental Quality
This webpage provides a brief introduction to septic systems, how septic systems operate, an inspection checklist for those who are planning to buy a property with a septic system, how to go about getting a new septic system installed, and a septic system maintenance fact sheet.

All About Septics | University of Minnesota Onsite Sewage Treatment Program
This webpage provides detailed information on septic system types (type i and iii systems), advanced treatment systems (type iv systems), special situations, and other onsite treatment areas of interest.

Septic System Basics Video: Septics 101 Course | Washington State Department of Health
This 19-minute video intended for homeowners explains the basics of how on-site sewage systems function and the steps you should take to keep your system working well. The video is divided into 5 chapters that can be viewed separately. Chapters include: Introduction and Sewage Overview, System Basics and Soil, Types of Septic Systems, and System Care & Maintenance.

Cleaning an Onsite Sewage System | Indiana Onsite Wastewater Professionals Association
This 2-page fact sheet provides onsite owners some basics about the system. These include: How an Onsite Sewage System Works, Inspection of the System, Cleaning the Outlet Filter, and Cleaning the Septic Tank. Additional references are also included in this fact sheet.

Septic Tank Pumping | Idaho Department of Environmental Quality
This 11-page manual was developed to help pumpers understand these important aspects of septage handling and disposal. Topics covered are: Septic System Components, Checking the Level of Scum and Sludge in a Septic Tank, Permit Requirements, Septic Tank Pumping, Equipment for Pumping and Transporting Septage, Septage Storage, and Septage Disposal.

How to find more resources on this topic on our website?
If you are interested in looking through our database for other resources on this topic follow the instructions below:

1. Select "CATEGORY" in the dropdown then choose "Decentralized WW Systems." 
2. Once you make that selection, a second dropdown will appear where you can choose "TYPE" if you are looking for a specific kind of resource (videos, factsheets, etc.)
3. Optional: In the Keyword Filter, you can type a specific word or phrase to target the search even further.
4. The last step is to click the "Retrieve Documents" button to see your results.