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Installing Drainage

The decision on whether to construct your drains once you have reached oversite or damp proof course (DPC) level with the underbuilding is a tricky one. It may seem best to get drains out of the way and backfilled at the same time as all of the other groundworks are taking place. On the other hand if work on the superstructure is to continue, they may be in the way, prevent the erection of scaffolding or get damaged by the ensuing works.

There are two main functions of your Drainage: The first is to dispose of 'foul water' the domestic waste from bathrooms, toilets and sinks etc. The second is to deal with 'surface water,' the rainfall from the roof etc.

Foul Drainage

Foul drainage is best disposed of to the ‘mains drains', which may be adopted or private at the point of connection. If mains drainage is available you will be required to connect, even if this is not the cheapest option. If a sewer is not available there are at least three other options:

  • An on site septic tank. This passes partially treated effluent into subsoil irrigation.
  • A treatment plant. This passes more refined semi-sterile effluent into subsoil irrigation, a soakaway or a watercourse.
  • A cesspool. This is where the household effluent is stored for collection and off site disposal.

Surface water is usually dealt with by taking it to soakaways constructed 5 metres from the home. These are often simple holes filled with rubble but in areas of poor drainage may have to be more complicated brick or concrete chambers. If a watercourse is available, this is the best option. Consider recycling your rainwater, not only is it ecologically friendly but with our partners tank and assembly kit it offers a simple alternative.

Surface Water

Most self builders opt for plastic type drainage, which is easier to handle on site and stand to test. Drains must be laid in carefully dug trenches and surrounded by clean pea gravel. All routes must follow straight lines and all changes of direction must be made at a manhole or inspection chamber. Falls are usually 1-40 but can go as low as 1-100 if plastic drainage is used. No drains can be backfilled before inspection and testing.

Next: Constructing your Subtrate or Under Building

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Installing Drainage

Installing Drainage

Key Points
1
The Environment Agency will need to approve the use of a septic tank, treatment plant or cesspool. They will expect you to have undertaken your own soil porosity test as evidence for your election.
2

Surface water is usually dealt with by taking it to soakaways constructed 5 metres from the home. These are often simple holes filled with rubble but in areas of poor Take care when siting off mains drainage systems as all of them need to be emptied or maintained at times and tankers can only reach 60 metres.

3

Consider recycling your rainwater, not only is it ecologically friendly but with our partners tank and assembly kit it offers a simple alternative.

4

Talk to your Key Account or Sales
Development/Branch Manager about the many different options for treatment which exist. In certain circumstances you may need to pump your drainage, our partners have specific products to help with this.

5

Our drainage sponsors, Hepworth Drainage, offer technical assistance on all drainage product ranges please contact our technical advisory service on: Tel 0870 443 5551 or
Fax 0870 443 5552.

Additional information from Hepworth Drainage

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