Rainwater goods or drainage is an essential part of your home in order to protect your house from water damage. The drains must also need to be hooked up to a suitably planned underground system.
1 - SELECTING MATERIALS
Unless specified most builders will revert to plastic drainpipes as they are cost effective and easy to install. Fitting downpipes can be a bit more complicated when the external walls ave more than one finish i.e tile hanging and brickwork. Other options to consider are galvanised still, aluminium, stainless steel, copper or glass reinforced plastic and cast iron.
2 - GUTTER DESIGN AND INSTALLATION
The roof slope must be carefully calculated so you know where to position the downpipes, gutters and outlets. The general calculation is the effective area of the room and multiply this by the litre of hard rain generated per second. Hard rain is defined as 75mm of rainfall in one hour.
3 - DISCHARGE POINTS
Rainwater must not contaminate the foul drains, so the two disposal systems must be kept separate. The uttering could be directed to a sewer, soaraway or irrigation system. In urban settings, sewers are really the only option.
4 - DRAINAGE INSTALLATION
Drain runs should never be flat. Pipes should be completely surrounded with pea shingle and a geotextile later fitted to protect the shingle from contamination by stones contained in the hardcore. Manholes will ideally. be inserted at every change of direction. Foul drains have to be tested to prove there are no leaks.
5 - MAINS SEWER CONNECTIONS
It's possible to tap into a nearby foul sewer, normally placed near the road and you may need to seek a quote from your local water company.
6 - NO ACCESS TO MAINS
If you are out in the country then you may to set up a private discharge option, which will have to comply with Enviroment Agency's requirements. The rules are changing and we have a page on our website giving you further information:
https://www.gov.uk/guidance/general-binding-rules-small-sewage-discharge-to-a-surface-water