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What is a septic tank soakaway?

Updated: Feb 13, 2023



A septic tank is a popular way to dispose of waste when you’re not connected to the main sewers whilst a soakaway is often built in as an efficient way to deal with the wastewater. Combined together, a septic tank soakaway is used to safely drain off treated wastewater that has been flushed from your home. It allows the effluent level in your tank to remain constant, whilst remaining organic solids break down with the help of bacteria in the system. The septic tank and soakaway are connected by pipes.


As with any system they need to be well maintained and can only be used in certain conditions.


How do septic tanks work?

A septic tank is typically connected with two pipes: an inlet pipe and an outlet pipe.

The inlet pipe is used to transport wastewater from the house to the septic tank. It’s then stored inside the tank, long enough for the solid and liquid waste to separate from each other, before exiting via the outlet pipe.

The outlet pipe removes the pre-processed wastewater from the septic tank, slowly dispersing it back into the soil and drain field.

Inside the tank, the wastewater separates into three layers - scum, wastewater, and sludge.

The top layer (scum) is usually oil, grease, and other fatty deposits. These will float above the wastewater and waste particles in the tank.

The bottom layer consists of particles that are much denser than the water and form a layer of sludge.

Bacteria will gradually eat away the sewage – reducing it to almost nothing.

The liquids in the tank will drain through a soakaway, and as this drains out, the effluent material remains in the tank.

The sludge at the bottom will need to be removed regularly, as part of general maintenance.

What is a soakaway?

In simple terms, a soakaway is a hole in the ground, filled with rubble. This is set away from the septic tank and wastewater is released into it and diffused through the rocks, slowly escaping into the ground. The soakaway provides a slow method of diffusion which stops pooling and helps to prevent flooding. This would work best in areas where it’s difficult for water to drain directly into the ground.

How long will a septic tank soakaway last?

Both septic tanks and soakaways need regular maintenance in order to keep them working efficiently.

Maintenance of a septic tank includes emptying of the tank sludge build up so the wastewater disposal system can still function. They should be emptied every 12 months and serviced every 6-12 months depending on if they start to smell - this can be the first sign of a problem. The soakaway should also be serviced every 12 months, alongside the septic tank.

It’s impossible to say how long a septic tank soakaway will last, but the better level of servicing, the longer it will work for.

How can we help?

At Cotterill Environmental, ​​we supply and install septic tanks and soakaways. We also provide a regular maintenance service to ensure your system stays in tip top condition.


Through our planned maintenance service, our team of experienced and qualified specialists will be able to identify any common faults and help solve issues before they occur as well as ensure your system is working to its full potential. Our team of specialists can provide you with expert advice. Call us today on 0121 461 4861.




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