Soakaways

All septic tank systems must be attached to a Soakaway system in order for the waste water to not only escape but also be treated before it enters the ground.

According to building regulations and the Environmental Agency, this has to be constructed in a very specific way.

For a waste water soakaway can not be constructed in the same fashion as a rain water soakaway, wilst a rain water soakaway can be a large pit full of medium or storm crates, a waste water soakaway has to drain off in a larger area using a circuit of trenches, not allowing all the water to collect in one place, instead spreading it evenly over a larger area

The length of the soakaway drains is determined by the number of bedrooms in the property and the porosity of the soil. New regulations state that for any house up to and including 3 bedrooms, the minimum size sewage system that can be installed is for 5 persons, with one extra person added for each extra bedrooms.

The porosity can only be determined by a percolation test which measures the time it takes for water to drop 1mm in the percolation test hole. From this time, known as a V Value, the length of drain required can be calculated.

Soakaways are required to be a minimum of:

• 10m from a watercourse or ditch
• 50m from water abstraction points
• 15m from any building, and sufficiently distant from any other soakaway, including roof water.
• 2 metres from a boundary

Other Regulations:

• The soakaway or drainfield area should be downslope of groundwater sources
• No watr supply pipes or underground services should be within the soakaway area
• No access roads, driveways or paved areas should be within the soakaway areas. This includes fields with tractors and agricultural vehicular traffic.
• The water table or bedrock must not, at any time, be within 1.2 metres of the bottom of the soakaway trench
• No rainwater must be allowed to enter the system – you might consider ”Rainwater Harvesting” instead.