Kitchen & bathroom
The washing machine discharges a large volume of water very quickly. If the shared kitchen waste run is partially blocked with fat and detergent scum, that surge has nowhere to go and pushes back up the nearest opening — normally the sink, because it is the lowest.
This is a classic partial-blockage symptom. Everything looks fine at low flow and fails at high flow, which is why the sink drains normally the rest of the time.
Clean the sink trap and the washing machine standpipe trap first. If the surge still backs up, the horizontal waste run needs clearing properly.
Detergent scum plus fat is a stubborn combination in a narrow 40mm waste pipe. Jetting restores the bore; a strainer and better fat habits keep it clear.
We're a small, family-run team based in East Grinstead, on call 24/7 across East Grinstead and a 20-mile radius. No obligation — tell us what you're seeing and we'll tell you straight what it is.
0330 1331 347Related service: Blocked Sink & Basin Unblocking
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