Septic Tanks and Systems Resource Guide

Use of Bleach in Septic Tanks

Bleach is an ingredient present in toilet bowl cleaners, which means it can easily end up in your septic tank. A limited amount of bleach will not harm your septic system, while excessive use can contribute to septic system failure.Septic tanks are like the stomach of a home’s digestive system. They process the wastewater coming out of it and release gases to the air as well as certain amounts of processed wastewater to the soil and groundwater. The care, use and maintenance of the septic tank are critical.

What Is A Septic Tank?

A septic tank is an underground tank usually made of concrete, polyethylene (plastic) or fiberglass. It is watertight and holds wastewater from your home. Solids are broken down over time into sludge, which settles toward the bottom of the tank while oils and grease rise to the top and form scum. An inlet tee and an outlet tee control the flow of what enters and leaves the tank. A nearby drain field further treats the wastewater.

Bacteria in the Septic Tank

Septic tanks contain wastewater products and prevent the solids and non-biodegradable components from entering the soil and groundwater. Anaerobic bacteria are those that live in environments without air. In the septic tank, they feed on the biodegradable matter and help reduce it to sludge. This process creates gases such as methane, hydrogen sulfide and carbon dioxide, which are vented to the atmosphere through the home’s plumbing vents.

Cleaning the Septic Tank

Septic tanks need to be cleaned regularly to function properly. The company that installed the tank can provide information on how often to clean, but the general rule of thumb is every three years. If the installer does not provide cleaning services, there are sure to be septic techs in your area. The job consists of pumping out the sludge and scum and must be done by a licensed professional. The tank should not be washed or rinsed out after pumping, as this can destroy the bacteria necessary to treat the wastewater.

Bleach and Other Household Cleaners

Small amounts of household cleaners, including bleach, drain cleaners and detergent, are not harmful to the septic tank system. Excessive amounts of these or any ammonia, lye, paint thinners, disinfectants, pesticides and water softeners can be harmful, as they disturb the bacteria balance in the tank. Without enough bacteria to process the wastewater, the tank will not function properly, and the risk to soil and groundwater contamination increases.

What Amount of Bleach Is Safe?

The amount of bleach used in a normal load of laundry — or the amount included in your toilet bowl cleaner — is considered safe for septic tanks. Laundry in general should be spread over several days of the week so as not to overwhelm the tank with large quantities of wastewater all in one day. This would apply particularly if bleach is being used in multiple loads.