When a drain blocks, one of the first questions is where the blockage is. That is much easier to answer if you know where your drains run and where the access points are.
What you are looking for
- Inspection chambers: covered access points into the underground drain, usually with a square or round cover. Older ones are brick-built with metal covers; newer ones are often plastic, with a smaller round cover.
- Rodding eyes: small capped access points, often at the base of a soil pipe or where a drain changes direction.
- Gullies: open drains with a grating, usually below a kitchen or bathroom waste pipe or a rainwater downpipe.
- Soil and vent pipe: the large pipe running up the outside wall or through the roof, carrying waste from toilets.
Where to look
- Near the house, especially below bathrooms and the kitchen.
- Along the line between the house and the road, where the drain heads towards the sewer.
- At changes of direction or where two drains join.
- Front gardens and driveways, often just inside the boundary. Many terraced houses have the last chamber at the front.
- Under paving, decking, gravel and lawns. Chambers are often covered over during garden work. A metal detector can help find old metal covers.
If you live in a terrace or a semi-detached house, the drain may run under neighbouring gardens before reaching the sewer. See who is responsible for a shared drain.
Working out which way the drain runs
Drains run downhill, usually in straight lines between chambers. With covers lifted, you can often see which direction the channels at the bottom of a chamber point. Running a tap or flushing a toilet and watching which chamber the water appears in helps you trace the route.
Only lift covers if you can do so safely. Covers can be heavy and edges sharp, and never leave an open chamber unattended.
Where to find drainage plans
- Your property deeds or purchase paperwork. A drainage and water search from when you bought the house may show public sewers near the property.
- The water company. Water companies keep maps of public sewers. In most of Hampshire that is Southern Water; Bournemouth, Poole, Christchurch and Salisbury are served by Wessex Water.
- Building control records for newer houses and extensions may include drainage drawings.
These records usually show public sewers, not every private drain within your property.
When to get the drains mapped
If chambers have been lost under paving, or you are planning an extension, a CCTV drain survey can trace the drains and show their condition. That is also useful before building over or near a drain.
If your drains are blocked and you cannot find the access points, we can help. See blocked drains.