Water heater supply pipe leak

Symptoms

• Water pooling at the base of the water heater
• Drip visible at a fitting on the inlet or outlet pipe
• Rust or mineral crust building up around a connection
• Water heater's drain pan (if present) has water in it

Likely causes

• CommonLoose or corroded compression fitting on the supply linesThese connections can loosen over time or corrode, especially with older flexible connectors.
• CommonFailing shutoff valve at the cold water inletValves used to isolate the water heater can develop leaks at their packing or body over years.
• PossibleCorroded or cracked dielectric unionThese fittings connect copper pipe to the water heater's steel nipples and can corrode from the dissimilar metals.
• PossibleLeak actually originating from the tank itself, not the pipesIt's important to distinguish a pipe leak from a leaking tank, which is a different and more serious problem.

What to do

1. Turn off the cold water supply to the water heater at its dedicated shutoff valve.
2. Dry all surfaces around the water heater and connections, then watch closely (or briefly restore water) to find the exact leak point.
3. If the leak is at a fitting, try tightening it carefully with a wrench, but avoid overtightening older or corroded fittings.
4. If tightening doesn't stop it, shut off water fully and drain the connection to replace the fitting, gasket, or valve.
5. Wrap new fitting threads with plumber's tape or apply pipe joint compound as appropriate before reassembling.
6. If the water is coming from the tank itself (check the tank body, not just pipes) rather than the connections, this typically means the tank is failing and needs replacement, not a pipe repair.
7. Turn water back on slowly and monitor the area over the next day for any recurring drips.

Tools and parts

• Adjustable wrench
• Plumber's tape

When to call a pro

Call a plumber if the leak is from the tank itself rather than the supply pipes, since that usually means water heater replacement.

Safety