What Cleaners Not to Use in a Septic Tank

Nick Davis

Septic tanks and their drainfields are mini-waste management systems that work similar to a city's sewer system. The only difference is you have to treat the septic systems by pumping the waste out of the below-ground units every four years and properly maintain them by not using a large amount of water or certain cleaners and chemicals. Cleaners like septic tank cleaning solutions, drain cleaners and excessive amounts of household cleaners should not be poured into a drain and flushed into the septic tank system.

Septic Tank Cleaners and Additives

Septic tank cleaners and additives should not be used to treat your septic tank and drainfields. The solutions include bacteria, enzymes and yeast, but the cleaners/additives do not reduce the need for pumping your septic tank or properly maintaining your drainfields (by not parking vehicles or heavy equipment over the drainfields). Some septic tank cleaners contain organic chemicals that may damage your septic tank, drainfields and contaminate wells and groundwater.

Household Cleaners

Do not pour a excessive amount of household cleaners like bleach, laundry detergent, cleansing powder or other chemicals into your septic tank. Your septic tank contains waste-eating bacteria and these cleaners can reduce the amount of bacteria present in the septic tank. The level of bacteria within the tank fluctuates and recovers quickly if small amounts of household cleaners are used. Over time, excessive amounts of these cleaners can destroy all levels of bacteria within the septic tank system.

Try to use household cleaners that have “Warning” on their labels — these cleaners are moderately hazardous. If the cleaner has “Danger” or “Poison” on its label, these are highly hazardous and should not be used. “Caution” means the cleaner is slightly hazardous to your septic tank.

“Nontoxic” and “Septic-Safe” means the products are safe for your septic tank, but follow the instructions on the label and only use the recommended amount of cleaner noted on the label.

Drain Cleaners

Do not use caustic drain cleaners to open a clogged drain. Use boiling water or a plumber's auger (sewer snake) to open the clogged pipe. If a sewer snake is not available or you don't know how to use one, consult with a plumber or septic tank repair service.


Do not pour excessive amounts of water into your septic tank system. The water can overfill the tank and cause possible damage and reversal of waste. Do not pour oils, fats or cooking grease down any of the drains in your house. Substances can cause issues with the septic tank.

Also, paints, paint thinners, solvents, pesticides, poisons and other chemicals should not be poured into a drain or allowed to be entered into the septic tank/drainfields. These chemicals can kill the bacteria within the septic tank and kill soil microorganisms around the septic tank and drainfields, as well as contaminate the groundwater.