Sewage and water are inextricably linked. If the one is not handled properly it can pollute the other which is why the Arun & Rother Trust is so interested in waste as well as water.
West Sussex is a lovely part of England with some idyllic rural areas. For residents lucky enough to live in these areas, sewage disposal can be a real issue especially if there is no public sewer to take the domestic drainage away.
So, what are the options for a single house with, say, four people?
In the world of rural drainage, a cesspit is the least preferred option but in certain locations near public and private water supply boreholes there is no alternative.
A cesspit or cesspool is an enclosed tank with a minimum capacity of 4,000 gallons (18,000 litres) and should have no outlet or discharge to the environment. The risk of polluting the water source is too great hence no discharge will be allowed.
The tank is required to store all wastewater from the property and will need emptying very regularly perhaps once a month or more and this can be expensive.
Septic Tank with subsurface irrigation system
In some locations a cesspit will be the only feasible system but in other situations a septic tank may be a possibility. Generally, installation and maintenance costs are significantly less than a cesspit.
A septic tank is much smaller in capacity (600 gallons/2720litres) and usually has two chambers that allow the domestic sewage to settle before the liquid fraction is allowed to drain to a sub-surface network where it soaks into the ground.
However, correct installation is very important. The sub surface irrigation system is crucial for the operation of this tank and a percolation test should be carried out to ascertain that the soil structure is satisfactory to soak the liquid away. The water table must not be too high to allow “flooding” of the soakaway and the irrigation system must be positioned away from any river or waterbody to prevent a short circuit resulting in a polluting leak. This type of drainage system will not be allowed near a water supply borehole
Package Sewage Treatment Plant
A few decades ago, where the soil conditions would not allow a septic tank a further level of treatment was added in the form of a trickling filter bed. The settled sewage from a septic tank was irrigated over the surface of clinker bed and a biological system established which would treat the sewage to a much higher standard. It was clean enough, after settlement, to allow a discharge direct to a ditch/watercourse.
The active ingredient here is air (oxygen) which allows the biological bugs and beasts on the clinker to flourish and clean up the settled sewage. Without this air the system would very quickly become anaerobic and the characteristic smell of bad eggs would prevail.
These days a package treatment plant can be delivered on the back of a lorry. After plumbing to the foul drain and given an electricity supply the unit is ready to go. In these ‘plug and play’ systems the bugs and beasties get their oxygen from a range of techniques. Some systems pump air directly into the domestic sewage others have plates that rotate half in the liquid, half in the air.
Installing these systems is not cheap, but it is relatively simple. However, the absolutely critical issue is size. It really does matter. The treatment plant must be sized correctly according to the number of people using the unit otherwise it will fail, and the smell of bad eggs will rule!
The Environment Agency has produced “general binding rules” which you must follow if you operate a septic tank or sewage treatment plant. A new installation will require Building Regulations approval and may possibly need Planning Permission.
Don’t waste the environment
I’ve spent my life up to my neck in sewage and other waste.
I’ve never found sewage a great party conversation piece, but I cannot overemphasise its importance. Effective Rural Drainage protects the Environment.