By Michael Hines, M.S., P.E.
Great news: You’re buying a new house! You’ve dreamed of a beautiful family home surrounded by open space, fresh air and a healthy environment with children running barefoot on the grass in the sun. And now your dream has come true. Today, for 40% of us who invest most of our lifetime earnings in this dream, our new home will come equipped with a septic tank system to process human waste.
Please don’t be put off by the term “human waste.” As a homeowner or local regulator, you need to know about human waste and how to properly treat it for one very important reason: Improperly treated human feces are the prime breeding ground of potentially deadly diseases (see the online-only sidebar “Where Cholera, Typhoid, Polio & Hepatitis Breed” on NPCA’s website at www.precast.org/ASTM-C1227). This means that septic tanks are critical issues – they can be buried but should never be forgotten.
Well-built and well-maintained septic tanks systems are remarkable engineering designs. In fact, efficient, properly managed on-site wastewater treatment systems that include a septic tank system built to industry standards are a healthy, natural and environmentally responsible way for a homeowner to process wastewater from toilets, showers, washing machines and sinks.
What happens when septic systems fail: it isn’t pretty
Let’s look at this picture: A beautiful new home is the holiday scene for a growing young family. All the relatives and friends are over, but there’s been a most embarrassing, inconvenient and smelly surprise: The septic system has failed. How could this have possibly happened? This is just inside your home – more bad news awaits outside.
Perhaps unnoticeable at first, soggy, unsanitary soil above the system’s failed drain field may be lying in wait for unsuspecting children or the family pet. No matter where the failure occurs, you are facing not just potential health risks, you are looking at a major repair expense (see the online-only sidebar “Septic Tanks: What They Are and How They Work” on NPCA’s website at www.precast.org/ASTM-C1227).
Seven typical causes of septic system failure:
- The septic tank is not designed or constructed according to standard to be watertight and structurally sound.
- The septic tank is too small for the number of people and the wastewater flow served by the tank.
- The septic tank is not properly maintained; tank solids have built up and discharged to the drain field causing clogging failure of the field.
- Excess flows are discharged into the tank, often from nondomestic sources.
- Toxic chemicals, large volume of solids, or other materials besides sewage are discharged into the septic tank.
- The drain field is too small for the intended use, or drain field soils are inadequate to treat and move flows away from the site.
- The drain field is poorly designed or installed and does not allow equal distribution of the applied flow across the field.
ASTM C1227: because now you want only a quality septic tank
Now that you understand why human waste must be treated properly and why you never want your family to experience a septic system failure, how can you make sure that your tank meets the highest industry standards? A consumer or a regulator needs to know one fact: Quality septic tanks are structurally sound and absolutely watertight and comply with the industry standard for design requirements, manufacturing practices and performance requirements: ASTM C1227, “Standard Specification for Precast Concrete Septic Tanks.”
An oversimplification? Actually, no. Just as you’d expect your roof to leak if you chose a poor-quality shingle and an unqualified roofer, a poorly made septic tank can fail because of a poor design, nonstandard manufacturing or slip-shod installation. Septic tank failures can result in dangerous situations, from a cave-in to contact with untreated human waste.
Obviously ASTM C1227 is not the only standard for septic tanks. In some states and localities, this standard may be adopted by reference into the state and local codes. When there is adequate enforcement and oversight, regulatory agencies act on the citizens’ behalf to make sure all producers of septic tanks meet the standard. Some state and local ordinances define their own standards and require septic tank producers to comply with regional specifications to be certified.
So the problem − and it is, unfortunately, a widespread problem − is that ASTM C1227 is not referenced consistently by all septic tank regulatory agencies – state, province or local. To make matters worse, even where ASTM C1227 or comparable regional standards exist, septic tank inspectors and regulators do not always enforce the standard. In fact, many regulatory jurisdictions pay lip service to standards that clearly describe how septic tanks are to be designed and constructed to be structurally sound.
Enforcement and economics: the dark side
While some inspectors may specify (on paper) that tanks within their jurisdiction must be structurally sound and watertight, these regulators do not enforce (in practice) the requirement. As a result, thin-walled tanks with little or no steel reinforcing are installed every day; there might even be one in your own backyard.
Installers of poor-quality tanks know that they are relying on the subsoil for structural support. Without the soils that surround it and hold it together, a poor-quality tank will collapse when filled with water. On the other hand, a quality precast concrete septic tank built to standard is structurally sound before and after installation. So what incentive drives some producers to market tanks that are not watertight or structurally sound?
For too long, septic tanks have been treated as a commodity rather than as an engineered product that requires skill and care in manufacturing. As a commodity, septic tanks are typically purchased based on cost alone − often the cheapest price available. As a homeowner or home builder, you would be well-advised to consider the relative economics of paying $30,000 to $50,000 for a top-of-the-line kitchen with all latest appliances while settling for a cheap, poorly constructed septic tank that could endanger your family’s health and lead to expensive remediation down the road (see the online-only sidebar “Expert Tips for Purchase of a New or Existing Home with a Septic System” on NPCA’s website at www.precast.org/ASTM-C1227).
With all the regulatory programs around, why are there so many septic tank problems?
In the real world, many poor-quality septic tanks are installed every day and yes, these are the tanks that are likely to fail structurally and create health and environmental risks. Here is the inside track to help you understand the current dilemma:
- By their nature, septic tank regulatory programs are very politically sensitive; tank manufacturers resist any strengthening of requirements/standards that will increase cost of production.
- Homeowners often choose the lowest-cost system available.
- When a system fails (often the property owner has no lot space left for system repair), the regulator’s only options are to:
- Enforce the regulations that may include possible eviction, or
- Ignore the failure (regulators seldom return to malfunctioning systems unless neighbors’ complaints force subsequent inspections).
- Many regulators are poorly trained in the science of wastewater treatment, septic tank design or tank maintenance requirements. Typically, regulators are handed a “cookbook” set of rules to apply to every situation regardless of differences in sites, soils, tanks and drain field installations.
- Many jurisdictions in the United States operate on standards and regulations that have been essentially unchanged for 20 to 40 years. Modern advancements in treatment or disposal technologies go unrecognized until mandated by changes in political perceptions.
- Not all state and local regulators have adopted industry standards like ASTM C 1227, and not all septic tanks are manufactured by NPCA-certified precast plants.
- Not all septic tanks are made of steel-reinforced precast concrete or fiberglass-reinforced plastic and therefore are not structurally sound and watertight.
How to maintain your septic system (and what will happen if you don’t)
Now that your septic tank is installed and in use, what do you do to protect the tank and care for it? If you simply forget the tank and pay no attention to it, one of these days you will be standing in your mucky, stinky yard while some burly guy with a backhoe digs holes in your lawn as dollar signs flash in front of your eyes. Septic tanks require inspection and maintenance if they are to function properly over their expected service life of 50 years. See the sidebar “9 Steps to Properly Maintain Your Septic Tank System.”
Conclusion and responsibilities
Many players are involved in providing you with a quality septic tank system:
- The engineer who designs the tank construction must be competent in concrete and structural design.
- The manufacturer must adhere to the engineered design, use quality materials and exercise quality control throughout the manufacturing process.
- The installer must be competent and install the tank in such a manner to ensure the integrity of the tank and watertightness of the connected system.
- The regulatory inspector must enforce diligently to ensure that all tanks within his or her jurisdiction are constructed, installed and maintained in accordance with competent regulatory requirements.
- The homeowner must provide attentive (not passive) care and maintenance of the septic tank system for as long as he or she uses the residence.
Providing a quality septic tank system involves choices and choosing quality septic tank components and materials from certified manufacturers, and it ensures the value of the owners’ investment in the home, the safety of his or her family and the protection of our environment.
Michael Hines, M.S., P.E., has 44 years experience in the field of wastewater engineering as a statewide regulator, a Tennessee Valley Authority environmental manager and a consulting engineer. He is founding principal of Southeast Environmental Engineering LLC and president of Utility Capacity Corporation Inc., a construction company. Hines serves on the Board of Directors of the National Onsite Wastewater Recycling Association (NOWRA) and its National Model Performance Code Committee.
Sidebar 1: 9 Steps to Properly Maintain Your Septic System
Quality precast concrete septic tanks, while structurally strong and watertight, must be maintained and serviced for long-term, trouble-free operation.
- Make sure the sizing of the septic tank and the septic system match the features of your home. If the permit calls for a three-bedroom system, don’t remodel and make an office or den into another bedroom. Septic tanks are sized to allow collection of all the wastewater and allow settling of the solids. Exceeding the designed limits reduces the ability of the septic tank and drain field to function.
- Make sure that the amount of wastewater entering the system does not exceed the permit design for the operation of the dispersal field. In North Carolina, for example, a three-bedroom design means the dispersal field is sized for 360 gal./day (1,360 L/day). This is 120 gal. (454 L) per bedroom assuming two people per bedroom (60 gal. or 227 L/person/day). Unfortunately, every locality uses different design rates. Some design rates provide very large safety factors; others are designed based on “personal preference” and may have little basis in science or engineering. Regardless of the validity of locally established design rates, they must be followed.
- First rule of septic tanks: Nothing goes into the septic system that has not first gone through your digestive system (or was intended to). Do not discharge paint, motor oil, cigarette butts, chewing gum, rug cleaners, bleach, drain cleaners, large volumes of cooking oils or grease, or anything else toxic to your septic system’s working bacteria. Cleaning and laundry using normal amounts of disinfectant, detergent, softener and bleach should not pose a problem, but any of these products used in excess can effectively “kill” your septic tank’s biology. A septic system relies on viable bacteria to breakdown human waste. Killing the bacteria means removing the ability of your septic system to function – never a pretty sight.
- Do NOT use commercial additives in your septic tank. TV and radio airwaves are full of ads for miracle additives, enzymes and special bacteria to add to your septic tank to make it work better, smell like flowers and look good. These products are, at best, a waste of money and can be harmful to the biological processes in the tank or drain field. Historically, EPA and other professional organizations have determined that such additives have not been shown to serve any useful purpose. Business development seminars held for the septic tank installers and pumpers encourage the sale of such additives to homeowners as a high-profit revenue source for the industry. Ignore such sales pitches.
- Routinely inspect your toilets and make sure they are not leaking. Leaking toilets are the No. 1 cause of hydraulic failure of septic tank systems. A single toilet leaking just ¼ gal. (1 L) per minute adds 360 gal. (1,360 L) in 24 hours, the full design flow for a three-bedroom home.
- Have your septic tank routinely pumped. The usually recommended clean-out schedule is every three to five years (or longer if you have a bigger tank). Have the clean-out done by a professional septage firm, making sure it services and reinstalls the effluent filter (if installed) and make sure all access devices are secured back into place.
- Absolutely no down spouts, AC condenser drains or other clear water discharges are to be connected to your tank. Water softener regeneration backwash should be diverted around the tank to a separate seepage pit.
- Limit garbage disposal use. Some regulatory jurisdictions try to prevent garbage disposal units in homes with septic tanks. Most homeowners will have a garbage disposal whether it comes with the house or is added later. The solution is to size the septic system to handle the extra solids produced by these devices. All residential septic tanks should be a minimum of 1,000-gal. (3,785-L) capacity; larger tanks are required if garbage disposal units are planned or as the number of occupants in the house exceeds eight.
- Inspection checklist: Your annual inspection should check:
- Depth of sludge and scum
- Condition of scum layer
- That the inlet tee is clear
- Proper operation of any installed pump
- Cleanliness of any effluent filter present
In addition, your drain field or drip area should be walked to check for any wet or soggy spots that would indicate pending or actual system failure.
Sidebar 2: Checklist for Quality
Your quality septic tank should meet this 8-point checklist:
- The manufacturer of your tank should be willing to show you certification by a professional engineer that the tank you are purchasing was designed in accordance with appropriate recognized standards and engineering principals.
- Your tank should be one piece or a monolithically poured body with a separate lid that is permanently affixed to the body with a watertight seal.
- The tank should be made of high-strength concrete (minimum of 5,000 psi [35 MPa]) and contain sufficient steel reinforcement to ensure the structural integrity of the tank at full design operating conditions.
- To ensure watertightness, the inlets and outlets must be equipped with rubber boots integrated into the tank wall (inlet and outlet pipes pass through these boots and the boots sealed against the pipes with stainless steel clamps).
- The inlet inspection plug in the tank lid should be sealed to the tank with high-quality mastic or other sealant that will prevent water leaking into the tank.
- The inlet inspection riser must be cast as part of the tank lid and a watertight riser extended to the ground surface and be equipped with a watertight cap.
- If the tank is not equipped with an effluent pump, an effluent filter should be installed on the outlet.
- A 24-in. (610-mm) diameter riser ring should be poured in the tank lid over the tank outlet to allow access to the pump or filter. A watertight riser must be permanently sealed to the riser ring, extended to grade and be equipped with a locked or bolted watertight lid.