Absorption Trenches are Crucial To Your Septic System, Don’t Risk a Quick Fix

What Size Does My Absorption Trench Need to be?


he size of your Absorption Trench depends on several very important factors.

This includes the load you will be placing on your absorption Trench and the type of soil where your absorption Trench will be installed.

The ability of your absorption trench to be able to it easily handle the load of liquid that will be pouring into it every day is crucial to its effectiveness and the longevity of your absorption trench to keep you safe.

The amount of effluent flowing into your absorption trench along with the ability of the surrounding soil to disperse the liquid waste from your septic tank (through soil percolation and evaporation) will determine its size.

Too small a trench will be overloaded by your septic system, resulting in effluent appearing on the ground on or around your trench making it unsafe as well as shortening its life considerably.

For example, if your septic system typically handles 300 litres per day, this means that your absorption trench will also need to be able to dispose of 300 litres of effluent every day.

Let’s suppose on average the soil around your trench can handle about 40 litres of water per square metre per day.

To handle the 300 litre output from your septic system, it is 300 litres divided by 30 litres per square metres per day (300/30).

This means the base of your trench needs to cover 10 square metres to completely absorb all the effluent on any given day.

Now if your trench is 500 millimetres wide the length of your absorption trench will need to be is 20 metres.

20 Metres long by 500mm wide = 10 square metres.

I hope this helps answer your question about “What size your absorption trench needs to be?”.

For more information about your absorption trench size or a related matter please feel free to give me a call. I will be happy to help.

And be sure to leave me a message if you catch me on the job. I will get back to you as soon as possible.

Yours Sincerely


Paul Burgess absorption trench expert

Paul Burgess (0438 315 514)



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