The folklore of treatment systems could probably fill a small book. Like most folklore, the stories reflect elements of truth, ignorance, and humor. The purpose of this page is to dispel some myths about treatment systems and explain how they actually work. Hopefully, this information will help you keep your system working well for many years.
The treatment system, more appropriately called an onsite wastewater treatment system, is a natural treatment system. By natural, we mean that it relies on bacteria to digest and clean the wastewater (sewage). The bacteria in the treatment (treatment) tank literally eat the solids in the tank turning them into liquids and gases. As you might expect, these gases have a foul odor. To manage these bad odors they are vented off through pipes on the house roof. The liquid wastes then either flow to the dispersal field, or if more treatment is necessary, through some form of secondary treatment system. The final purification occurs by organisms living in the soil.
The bacteria in the treatment tank eat and digest most of the waste. But there is always some waste that doesn't even appeal to these critters. This undigested waste builds up as sludge in the bottom of the treatment tank. As a result, it is recommended that you have your treatment system pumped every three to five years. This will remove excess sludge that has accumulated.
If you have one of the "Alternative" treatment systems (i.e. Low Pressure Distribution, Drip Irrigation, Spray Irrigation), or a system that required secondary treatment (i.e. AdvanTex, PuraFlo, Sand Filter, Aerobic Treatment), then annual maintenance and oversight should be performed. Having a "mechanical" component adds complexity to your wastewater treatment system, and like changing the oil in your car, preventive maintenance should be performed at least on an annual basis. Waiting until there is a problem can cause irreparable damage to the soil dispersal component of your onsite wastewater treatment system.
Theories abound about the best way to start-up a new treatment system. Most theories deal with "seeding" the primary treatment tank to get a good bacterial growth started. Advice has ranged from flushing a pound of yeast into the system, to seeding the treatment tank with manure, all the way to placing a dead cat in the treatment tank. We do not recommend any of these.
Most of this folklore is believable because it contains elements of truth. The concept of seeding a treatment tank is partially true. Treatment systems are biological systems and must have bacteria to work. However, no special seeding is necessary to get them started. The simple act of using the system will provide all the bacteria necessary to make the system function. Yeast, manure, and especially dead cats will not help develop the colony of bacteria in the tank any faster.
Treatment system folklore doesn't stop with seeding a new treatment system. Many products are sold that claim to make old systems like new. Other products claim to eliminate the need to pump out the treatment tank. These products usually contain yeast, bacteria, enzymes, or chemical degreasers.
People often ask if additives can reduce or eliminate the need to pump a treatment tank. It's a good question, too. So far, no additive has been proven effective in a controlled scientific study. Many company's make claims that their additives work, and may even be able to provide you with a brochure that says they have been laboratory tested and proven, but it was their lab!
Some of the solids in the tank are sand, grit, bits of plastic and similar materials. No enzyme or bacteria can digest these. There are even some organic solids that cannot be broken down in the tank. Hence they accumulate. When you add commercial products to your system, the bacteria they add must compete with bacteria that are adapted to living in your treatment tank. These adapted bacteria have the home field advantage. The newly added organisms can't compete and become dinner for the resident organisms.
Enzymes on the other hand, unlike bacteria, are not living and cannot reproduce. When they are added to a system, they will not increase in number. Most treatment tanks are 1,000 gallons or larger, and the quantity of enzymes added is generally too low to be helpful.
In short, adding enzymes or bacteria usually won't cause a problem, but they won't help either. The solution is simple. Pump your tank every three to five years, and if you have an "alternative" system, arrange for annual maintenance and monitoring. This solution is easy, safe, and often cheaper than continually buying treatment tank additives.
After a conventional system is working, it requires very little maintenance. About all you have to do is pump the tank out every three to five years. The purpose of pumping out the tank is to remove the accumulated solids. These solids can and will stop-up the soil where the wastewater is to be absorbed, filtered and treated. When you have your tank pumped, it is wise to inspect the condition of the tank. Your licensed treatment tank pumper can check the condition of the treatment tank and the pipes going into and out of the tank. An "alternative" treatment system on the other hand has other components that need to be checked and monitored. Your local treatment tank pumper may or may not have the experience to deal with these types of systems.
An annual preventive maintenance inspection or Operation & Maintenance Inspection should involve examining the treatment tank to determine whether it needs to be pumped, examining and testing the float controls for any pumps involved, examining the filter system and the media that it utilizes to determine that it hasn't become clogged or that grease isn't bypassing the treatment tank. Checking the motor control panel to determine that the alarm function is operating, and that the pump is operating as it should and pumping the correct amount of effluent to either the filter, or the dispersal field.
The most often heard myth though is the concept that, "I never had to have my treatment tank pumped before. And I sure don't need to start now!" This reflects an unfortunate attitude of neglect. Another way of looking at it is, "If it ain't broke don't maintain it." Your local health department certainly doesn't promote this attitude, and neither do we. We prefer to think of it like changing the oil in your car. It is always wiser to perform some "preventive" maintenance before the system stops working.