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Building Regulations

This section has been written for homeowners who may be considering building an extension or making alterations. It outlines the main impacts that drainage may have on your project. If you decide to proceed with your project, your builder will need to look at Approved Document H1 for detailed advice on how to comply with building regulations.  

What is drainage?

There are two systems of drainage that you need to think about: 'foul' and 'surface water'. In general, these two systems should be kept separate.

Each of these has above-ground and underground elements.

  • Foul drainage carries the used water from toilets, sinks, basins, baths, showers, bidets, dishwashers and washing machines. The above-ground pipework is referred to as sanitary pipework; the underground pipework is referred to as foul drains and foul sewers
  • Surface water drainage carries rainwater (and melted snow and ice) from hard surfaces. The above-ground system of gutters and rainwater pipes is referred to as roof drainage; the underground pipework is referred to as surface water drains and surface water sewers.


What is the difference between a drain and a sewer?
Why do I need to think about underground drainage?
How can I find out the location of underground drains and sewers?
I’m thinking about increasing the size of my roof
I’m considering a new patio or driveway
What size pipes do I need from kitchen and bathroom appliances?
Do I need a ventilating pipe through the roof?


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    1. https://www.planningportal.co.uk/applications/building-control-applications/building-control/approved-documents/part-h-drainage-and-waste-disposal

    The Planning Portal is delivered by PortalPlanQuest Limited which is a joint venture between TerraQuest Solutions Limited and the Department for Levelling Up, Housing & Communities. All content © 2022 Planning Portal.

    The Planning Portal is delivered by PortalPlanQuest Limited which is a joint venture between TerraQuest Solutions Limited and the Department for Levelling Up, Housing & Communities. All content © 2022 Planning Portal.