Will chemical drain cleaners damage the septic system?

Chemical drain cleaners can be very harmful to the good enzymes and bacteria in your septic tank which help to break down the sewage and treat the wastewater.

While manufacturers of store-bought drain cleaners would have consumers believe that the answer to a blocked or slow-draining drain was a couple of glugs of their product most plumbers and drainage specialists would not recommend their use. This is especially true if you are not connected to a council wastewater treatment system but treat your waste with a HSTP or septic tank.

Other products to avoid using in your drains if you have a septic system or home wastewater treatment plant include:

• Bleach
• Lye - sodium hydroxide or caustic soda - is often the active ingredient in many commercial drain cleaners
• Anything labelled ‘antibacterial’
• Ammonia
• Phosphates
• Petroleum-based chemicals

Septic safe methods of clearing a blocked drain

Hot water

If the blockage is caused by things like a build-up of fat, oil, grease (FOG) or soap scum and is located close to the drain opening the hot water method can be surprisingly effective.

Very carefully, slowly pour boiling hot water down the drain. Allow to cool and repeat if needed.

This method is great for drains that are slow but still draining somewhat.

You could also add a small amount of septic-friendly dishwashing detergent to help break up the oily substances.

Biological enzyme cleaner

The method uses enzymes to eat through the organic blockage or gunk. Follow the manufacturer's instructions for use.

These methods can be used routinely as a preventative process to keep your drains running freely.

We strongly recommend speaking to your plumber or septic specialist about your drain issues. They can provide specific advice to help protect the delicate balance of bacteria in your wastewater treatment system ensuring it continues to function effectively.