Oops… don’t do this (or, when not to use 'P' traps in waste pipes)

If you’re working on an extension and you find something like the above, you’ll need to put it right.

What’s the problem?

Using a ‘P’ trap at the base of a soil and vent pipe will cause the drain to block due to a build-up of solid waste.

How to put it right

A rest bend should have been fitted at the base of the soil and vent pipe. Plus, the branch leading to the vent pipe isn’t accessible, so an access point should be provided to the pipe or the junction.

How the waste pipe should look

If in doubt, seek advice from your local authority building control team.

Further information

Find your local team using the free post code search tool.

See also: Drainage pipes: What to do when your water won't go round the bend

Please Note: Every care was taken to ensure the information was correct at the time of publication. Any written guidance provided does not replace the user’s professional judgement. It is the responsibility of the dutyholder or person carrying out the work to ensure compliance with relevant building regulations or applicable technical standards.