Illustrative cutaway showing the sort of grease-and-food buildup that can restrict a kitchen waste pipe.
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Get quotes from local drainage specialists ↗Why it happens
Fats cool and cling to pipe walls, trapping food debris and narrowing the bore. Find out whether only the kitchen sink is affected or the outside gully is overflowing.
Older homes can have clayware pipes, later plastic repairs and altered connections in the same drainage run. A defect at one joint does not necessarily describe the rest of the system.
Useful evidence to collect
Find out whether only the kitchen sink is affected or the outside gully is overflowing. Where safe, take dated photographs and note which appliances still work normally. Never enter a chamber or work around foul water without appropriate training and protection.
What repair is proportionate?
A specialist may clear the local waste first and inspect further if the problem returns. A slow kitchen sink may be caused by the trap rather than the external drain. A sensible recommendation should match the defect found and explain why a smaller repair would not be enough.
Before you agree to major work
Get the proposed work and its limits in writing. For costly repairs, ask for photographs or survey evidence locating the defect and consider a second quotation. Where the affected run may be shared or adopted, check ownership before arranging privately funded work.