A straightforward leaking-tap repair may commonly cost around $80–$150, while replacing a cartridge, mixer or the whole tap can cost roughly $150–$350 or more. The final price depends on the tap type, parts required, plumber’s call-out fee, access and your location, with metropolitan or after-hours work often costing more. Turning off the isolation valve can limit water damage while you arrange help. For an accurate price, ask a licensed plumber for a written quote before work begins.