Bath Overflow Leaking Through Ceiling
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →If water has reached any electrical fittings (lights, fans, extractor) in the ceiling below, turn off the electricity to that area at the consumer unit before proceeding.
Bath overflow pipes and waste traps are a frequently overlooked source of slow leaks that only become apparent when water appears on the ceiling below. The overflow cover plate, the overflow pipe connection, and the bath waste trap are all common failure points.
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Most likely cause & what to check
Fill the bath to the overflow level and watch — does water appear on the ceiling? If yes, the overflow connection is leaking. If only the waste drain is used and water appears, the bath trap or waste pipe is the source.
To check the overflow: remove the overflow cover plate (usually two screws). Behind it is a flexible pipe connecting the overflow hole to the bath trap or waste pipe. Check the connection at both ends for cracks or loose push-fit connections.
The overflow cover plate itself is sealed with a rubber washer or silicone around its face. If the washer is perished, water runs behind the plate and down the bath panel. Replace the washer (£2–5) and seal the plate with a bead of silicone.
Check the bath trap (P-trap or bottle trap under the bath, accessible by removing the bath panel). Ensure the trap body and its connections are tight and not cracked. Tighten the slip nuts by hand — overtightening plastic traps cracks them.
Check the waste pipe run behind the bath panel for sagging sections or loose push-fit joints. Push-fit waste fittings can work loose over time, particularly if the pipe has not been properly clipped.
If the overflow flexible hose has cracked, replacements are available from plumbing merchants (£5–15). Measure the overflow hole-to-trap distance before buying.
Refit the bath panel and test by filling the bath to the overflow. Check the ceiling below carefully — some leaks take time to appear so check again after 30 minutes.
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