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septic tank lid in grass with hedge

can I use smol products with my septic tank?

13 Mar 2023

We’re often asked this here at smol HQ and the short answer is YES! All smol products are designed to be septic tank friendly and we thought we’d take a moment to explain why.

but first… what’s a septic tank?

A septic tank is a large underground container that collects and partially treats your household wastewater so that it’s safe to release out into the environment. Not every home has one as most are now connected to the mains sewage network, but if for example you live in a very rural area, there’s a chance you instead have a septic tank.

so how does it work?

  1. A pipe carries wastewater from your kitchen and bathroom into the tank.
  2. Bacteria break down the solid matter and the remains sink to the bottom as sludge.
  3. Oil or grease will float as a top layer that is called ‘scum’.
  4. The middle layer is what’s left - i.e. wastewater with some waste particles.
  5. This middle layer of wastewater is discharged through the soil which naturally removes bacteria and viruses.

but why does it matter what cleaning products i use? 

Your septic tank is actually a delicate bacterial ecosystem all of its own and in order for it to run smoothly and efficiently you really do need to take care not to drastically upset this critical balance. 


There are 3 things we recommend you remember when choosing household cleaning products to use safely with a septic tank. Let’s call it a septic tank ABC…


Avoid bactericides and chlorine bleach (they will kill off your tank bacteria).

Biodegradable products are best.

Clean without phosphates (they aren’t broken down and will end up in the environment).


Fortunately smol products meet all these requirements so are safe to use with your septic tank, and more importantly will keep those septic tank bacteria happy…

yes, bacteria can be your friends. 

The key to a healthy septic tank is keeping those bacteria content. They are the ones working hard to break down any solids in the system and their role is critical.


Strong cleaning chemicals like bleach and bactericides can wipe them out and this will cause a range of nasty problems like clogging of your septic tank and ongoing groundwater pollution.

a word about doing the laundry… 

Using your washing machine should not pose a problem to your septic tank as long as the detergent you are using is suitable and as long as you monitor your water use.

the right detergent.

Of course both non-bio and bio smol capsules are safe to use with septic tanks so rest assured your bacteria will stay happy.


As a rule liquid and capsule detergents are better than powder for these wastewater systems because traditionally powder detergents have used clay as an ingredient and this has been known to clog up the system.


And you’ll want to avoid detergents that contain bleach or include anti-bacterial properties as these will of course NOT be good for your bacteria.

monitoring your water use.

The one issue with using your washing machine is the quantity of water that is going to run into the system during the cycle. Too much water entering the septic tank in one go runs the risk of overwhelming the delicate ecosystem that has built up and ruining the work your bacteria has been doing!


Try to spread your laundry loads out across several days instead of doing load after load after load on one day.


You should also try to avoid using the shower or emptying a bath at the same time as your washing machine is running as this will add additional volumes of water into the tank simultaneously.


And when it’s time to pick a new washing machine - aim for a HE (High Efficiency) model that uses less water than older versions. 


Every month our customers help save nearly 100 tonnes of chemicals just from using smol instead of the big brands. Having a septic tank certainly makes you think twice about what you are rinsing down your sink so it’s good to know smol has you covered.