A leak under a sink can originate from the cold or hot supply connection, the tap tails, the waste fitting, the trap, the branch waste pipe or an appliance hose. The most common cause is a degraded compression washer or O-ring on the trap or waste fitting, which may be revealed only when the basin is used heavily. Slow leaks often cause damage to the cabinet base, adjacent flooring and joists before they are noticed. Building Regulations Part H1 and BS 6700 set out installation standards for sanitary waste and water supplies. Engineers usually address common causes by tightening or replacing compression seals, fitting fresh washers and confirming that the waste fitting sits true against the basin outlet. If the leak persists, the trap or branch may need replacement, and prolonged damp can warrant a damp assessment.
Leak under sink
Water leak beneath a kitchen or bathroom sink from waste pipe, trap or supply connection.
