Why Is My Water Heater Leaking?
QUICK ANSWER
A leaking water heater is usually one of three things: the temperature/pressure relief valve discharging from high pressure, the drain valve dripping at the bottom, or supply fittings at the top loose. A leak from the tank itself means the tank is failing and replacement is the only fix.
Water heater leaks come from specific locations, each pointing to a different problem and a different fix. Some are minor and inexpensive (drain valve, fittings). One is serious and requires immediate replacement (tank wall failure). Figuring out where the water is actually coming from is the first step. Here is how to identify each leak type and what to do about it.
Where is the leak actually coming from?
Wipe everything dry with a paper towel, then watch for fresh moisture. A leak from the top often comes from loose cold inlet or hot outlet fittings, or from a corroded anode rod port. A leak from the side typically comes from the temperature and pressure (T&P) relief valve. A leak from the bottom comes from the drain valve at the very bottom or, worse, from the tank itself. Trace the actual drip path carefully since water runs downhill and the apparent leak spot may not be the source.
What if the leak is from the tank itself?
A leak from the actual tank wall (not from a fitting or valve) means the tank has rusted through from the inside. This is the end of the water heater. There is no patch or repair that holds; the tank has to be replaced. Tanks usually last 8 to 12 years before this kind of failure. The leak typically starts small but worsens rapidly over days or weeks. If you have any standing water around the heater base and no visible leak at fittings or valves, plan for replacement within days to avoid a major flood.
What about the temperature and pressure relief valve?
The T&P relief valve (the lever sticking out the side of the tank) discharges water when pressure inside the tank gets too high. Regular discharges suggest your water heater thermostat is set too high, your home water pressure is too high (need a pressure regulator), or the tank needs a thermal expansion tank. Continuous slow dripping means the valve itself has failed and needs replacement (20 dollar part, 30-minute job). Never plug or block the T&P valve since it is a safety device that prevents tank explosion.
Is a water heater leak an emergency?
Small drips from valves or fittings are not emergencies but need attention within days to weeks. A leak from the tank itself is an emergency in the sense that it will worsen and can flood quickly. Turn off the water supply (cold water valve above the heater) and gas or electric power to the heater if you see active flooding. Then call a plumber for replacement. Any gas smell with a gas water heater leak is an immediate evacuate-and-call-gas-company situation.
Water heater leaks come from valves, fittings, or the tank itself. Diagnose the actual source by drying everything and watching for fresh moisture. Tank wall leaks mean replacement, no exceptions. Valve and fitting leaks usually have quick fixes under 50 dollars. Shut off water and power at any sign of active flooding, and treat gas water heater leaks with extra caution.
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