Why Is My Water Heater Leaking?
If water is actively pooling, shut off the cold-water supply above the tank and kill the gas (or breaker for electric). Then call 602-560-8989. Phoenix slab construction sends a leak straight to flooring.
Where the water comes from tells you what failed. Top near the discharge pipe means the T&P relief valve; bottom corner is a worn drain valve; loose top fittings mean an inlet/outlet connection. Pooling under the center is the tank itself, which is a replacement, not a repair.
Phoenix has a fifth, hard-water-specific failure: the anode rod corrodes in 3 to 5 years instead of the manufacturer's 5 to 7. If your unit is past year 6 and the rod has never been changed, call 602-560-8989. The leak is probably the leading edge of tank failure, and we will tell you whether to repair or replace.
Common Causes
Temperature & Pressure (T&P) Relief Valve
The T&P valve opens if tank pressure tops 150 PSI or temperature tops 210 degrees, so occasional drips after a heavy hot-water draw are normal. Continuous discharge usually points upstream: city pressure over 80 PSI with a failed PRV pushes the T&P open. Test at a hose bib before replacing the valve.
Drain Valve Leak
The drain valve at the bottom of the tank takes a beating from Phoenix sediment every time you flush. The OEM plastic valve eventually leaks at the washer; tightening the cap may slow it but replacement is the fix. We swap plastic for a brass ball-valve drain when we are already there, so future flushing does not damage it again.
Corroded Tank (Anode Rod and Glass Lining)
Steel tanks rust, and manufacturers fight that with a glass interior lining and a sacrificial anode rod that rusts on purpose. Phoenix water at 12 to 20 grains per gallon corrodes the rod in 3 to 5 years, versus 5 to 7 on softer water. Once the rod is gone, the lining (Bradford White's Vitraglas and equivalent proprietary linings) starts taking hits, and the steel underneath starts rusting through.
Loose Water Connections (Top of Tank)
The cold-water inlet and hot-water outlet at the top of the tank loosen with thermal expansion. Run your finger along each connection; real moisture means a leak, not condensation. Replace any flex line that is corroded green or white, since pinhole leaks tend to open at the worst time.
Internal Tank Failure (Bottom Leak)
If water is pooling under the tank and you have ruled out the drain valve and T&P discharge, the steel has rusted through. There is no patch for this; the tank must be replaced. The economic line is age: under six and you may have a manufacturer warranty claim; past eight in Phoenix water, replacement is the right call.
Condensation (Often Not a Leak)
Not every drip is a leak. Condensation forms outside the tank when cold incoming water hits hot, especially in winter when Phoenix tap drops to 55-60 degrees. To diagnose, dry the tank and skip hot water for 30 minutes; condensation reappears evenly, while a real leak forms a trail from one point.
What Should You Do?
Try This First
- If water is actively pooling, shut off the gas (or breaker) and the cold-water inlet to the tank. Drain the tank through a hose to a safe location if leakage is severe. Then call 602-560-8989.
- Identify where the water is coming from. Top of tank is the T&P valve or an inlet/outlet connection; bottom corner is the drain valve; center base is tank failure. The location dictates the fix.
- Dry the tank completely, skip hot water for 20 minutes, and watch for fresh moisture. Condensation forms evenly across the cylinder. A real leak forms a wet trail from a single point.
- Check the T&P discharge pipe at the floor. A few drops after a long shower is normal; continuous flow is not. Test incoming pressure with an inexpensive gauge; over 80 PSI means the PRV is failing.
- Tighten the drain valve cap finger-tight. If the valve still drips, replace it. We swap the OEM plastic for a brass ball valve when the tank is otherwise healthy.
- Find the heater's serial number on the rating plate. On most major tanks the serial encodes month and year of manufacture. Past six years in Phoenix water without an anode-rod check is the tipping point for tank-failure risk.
- Place a pan or tarp under the heater to limit floor damage. Phoenix slab homes leak straight to flooring. Older garage installs may have a pan; slab installs in living areas often do not.
Call a Pro If...
- Water is coming from the bottom of the tank with no traceable connection to a valve or fitting (the tank itself has likely rusted through)
- There is a large amount of water actively pooling on the floor or migrating to drywall and baseboards
- The T&P valve is continuously discharging (signals a stuck thermostat, a failed valve, or city water pressure above 80 PSI with no working PRV)
- You see rust, corrosion, or staining on the tank exterior, especially around the lower seam
- The water heater is more than 8 years old in Phoenix water and the anode rod has never been inspected or replaced
- You smell gas near the water heater. Leave the house and call 911 before calling anyone else.
- Flex-line corrosion (green or white) at the cold-water inlet or hot-water outlet, indicating a long-running drip that may open into a pinhole leak