Which Chemicals Are Safe for Your Septic Tank? And Which Are Not?

Here is a quick way to evaluate the effect that chemicals will have on your septic tank.  Keep in mind that the bacteria in your septic system, either anaerobic or aerobic, are what purifies the wastewater and makes it safe for the environment. 

If you introduce a chemical into the tank that kills the “bugs”, or even makes them “sick” so they quit digesting the waste, the tank will quit working.

First off, when you see a phrase like “Septic Tank Safe” on a bottle, realize that it doesn’t mean anything. There is no legal standard for what is OK to put into a septic system and what is not. 

One well-regarded septic tank scientist has published this cheat sheet for homeowners:

• Danger — If you see this word on the label of a chemical, it means the chemical will kill the bacteria in your septic tank. Avoid it, or use as little as possible.
• Warning — Means limited use should have a minimal effect on your septic system.
• Caution — Generally means the chemical will have little effect on your septic tank.

Note: While this information is believed to be accurate, conditions and micro-organisms inside each septic system are different and no chemical can be guaranteed to be safe.