Water Heaters
Why Is My Water Heater Leaking? Causes and What to Do
March 12, 2026 · 6 min read
A leaking water heater is one of the most common — and most stressful — plumbing problems we see in West Valley homes. The good news: not every leak means you need a new unit. Here's how to figure out what's actually going on and what to do about it.
First, make sure it's actually leaking
Condensation, a nearby appliance, or a dripping supply line can all look like a water heater leak. Wipe the tank and fittings dry, lay down some paper towels around the base, and check back in an hour. If water returns, you have a real leak — and the next step is finding the source.
Common causes of a leaking water heater
1. A leaking drain valve
The drain valve near the bottom of the tank can loosen or fail over time. It's often a cheap, quick fix — sometimes just tightening or replacing the valve.
2. Loose or corroded water connections
The cold-inlet and hot-outlet connections at the top can loosen or corrode. Re-sealing or replacing the fittings usually solves it.
3. A failing temperature & pressure (T&P) valve
If water is coming from the T&P relief valve, it may be doing its job (releasing excess pressure) or the valve itself may be faulty. Either way it needs to be checked — excess pressure is a genuine safety issue, not something to ignore.
4. A corroded tank (the serious one)
If water is seeping from the body of the tank itself, the steel has corroded through from the inside. This cannot be repaired — the tank has to be replaced. In Arizona's hard water, internal corrosion is the single most common reason older tanks fail.
What to do right now
- 1Turn off the power — flip the breaker for an electric unit, or set a gas unit's dial to "pilot."
- 2Shut off the water to the heater using the valve on the cold-water inlet. If you can't find it, use your home's main shutoff valve.
- 3Mop up standing water right away to protect flooring, drywall, and anything stored nearby.
- 4Call a licensed plumber to diagnose the source and give you repair-or-replace options.
Repair or replace?
As a rule of thumb: a leak at a valve or connection is usually repairable, while a leak from the tank body means replacement. Age matters too — if your unit is over 8–10 years old and leaking from the tank, replacing it is almost always the smarter investment. Our plumbers show you both options with upfront pricing so you can decide with no pressure. Learn more about our water heater repair and installation service.
How to prevent water heater leaks
- Flush the tank once a year to clear the sediment that drives corrosion — the single most effective habit for a longer-lasting heater.
- Check the anode rod every few years. This sacrificial rod corrodes so your tank doesn't; replacing a spent one can add years of life.
- Ask about an expansion tank. On a closed plumbing system, thermal expansion stresses the tank and valves; an expansion tank relieves that pressure.
- Consider a water softener. Reducing mineral content slows the sediment and scale that shorten heater life across the West Valley.
What does water heater service cost?
Costs vary with the problem and your unit, so we always quote upfront before any work begins. A minor valve or connection repair is typically a modest fix, while a full replacement depends on the type and size of unit you choose — tank or tankless. The important thing is an honest diagnosis first, so you're not replacing a heater that only needed a repair, or repeatedly repairing one that's better replaced.
Why Arizona water heaters fail early
Our hard water is packed with minerals that settle as sediment inside the tank. That sediment insulates the burner, makes the unit work harder, and speeds up corrosion. It's why water heaters across the West Valley — from Surprise to Goodyear — often need attention sooner than the national average. Annual flushing dramatically extends tank life; read more in our guide to Arizona hard water.
