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Will chemical drain cleaners damage the septic system?

Chemical drain cleaners can be very harmful for 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 - which is often the active ingredient in many commercial drain cleaners
  • Anything labeled ‘antibacterial’
  • Ammonia
  • Phosphates
  • Petroleum based chemicals
Need septic system maintenance? Let our septic system experts help you.

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 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.

Will chemical drain cleaners damage the septic system? Let our experts help you.

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Why Use Express Wastewater Solutions?


    Because we are not a manufacturer and not tied to one particular system we can always offer the best solution for your wastewater needs.


    Because we do this every day we have developed a close knit expert team for every step of the process – from plans and council paperwork to excavations, electrical and plumbing. We handle it all to make the whole process as stress free and quick as possible.


    Most people have never installed a home sewerage treatment plant and don’t know the next step, that is why we offer a free 30 minute phone consult with one of our experts to point you in the right direction.


    We handle your wastewater installation from start to finish we can deal with all the trades, council everything so you don’t have to worry about a thing.


    Have peace of mind knowing that Express are licensed, insured professionals that will do your job right the first time.


    Not sure what system is right for you, or want to know if your system is working properly? Just give one of our friendly wastewater experts a call and they will be more than happy to help.


    We will always look to repair your system rather than replace it if it does not need to be, which will generally save large amounts of money sometimes up to and over $10,000.