A pipe coupling (10) which comprises a coupling body (12) having an inlet end (22) for connection to a water outlet; an outlet end (24) for connection to a water inlet, and a liquid flow passage (26) which connects the inlet and outlet ends (22, 24) and which defines a water flow path (28) through the coupling body (12); a sealable filter and flow detector access opening (14) which is provided on the coupling body (12); and a filter element (16) and a flow detector device (20) which are removably receivable in the coupling body via the access opening and positionable on the flow path to extend across at least a part of the lateral extent of the liquid flow passage.