Where the water is coming from decides whether this is a $200 part or a replacement. How to tell the difference, and how to shut it down safely in the meantime.
A leaking water heater is one of the few plumbing problems that gets materially worse the longer you look at it, because a tank that has started weeping is on a one-way trip. The good news is that a decent proportion of “leaking water heaters” are actually leaking fittings, and those are cheap.
Dry everything, put paper towel down in a few places, and look again in twenty minutes. Where the paper wets first tells you most of what you need to know.
| Where the water is | What it usually is | Outcome |
|---|---|---|
| From the T&P valve on the side | Excess pressure or temperature relieving itself | Repairable — but find out why it is relieving |
| From the drain valve at the bottom | A worn or partly open drain valve | Repairable, cheap |
| At the flexible connectors on top | A failed connector or union | Repairable, cheap |
| From a fitting where pipe meets tank | A failed thread or gasket | Repairable |
| Weeping from the tank body itself | The glass lining has failed and the steel is corroding | Replacement — no repair exists |
| Pooled underneath with no obvious source | Usually the tank, sometimes condensation | Get it looked at |
If water is seeping through the tank wall itself, the job is a replacement. A glass-lined steel tank that has started corroding cannot be patched, sealed, epoxied or welded — and once it has started, the failure accelerates. The only question is whether you replace it on your schedule or at 2am on its.
A discharging T&P valve is often dismissed as “just a dripping valve”. It is a safety device doing its job, and it is telling you one of three things: the thermostat is running the tank too hot, the system pressure is too high, or the valve itself has failed.
The middle one is common in Portland. Where a service has a backflow preventer you have a closed system, and without an expansion tank every heating cycle spikes the pressure with nowhere to go. The T&P valve ends up absorbing that, cycle after cycle, until it fails. Fitting the expansion tank fixes the cause rather than the symptom.
A 50-gallon tank holds 50 gallons, and a failed liner does not leak politely. If the heater sits above finished space, or in a basement with anything stored on the floor, the water damage will comfortably exceed the cost of the heater. This is the argument for a drain pan and a real drain line, and for replacing a tank that is over ten years old on your terms rather than its.
Everything else — a slow drip at a fitting, a damp drain valve — will keep safely until morning with the water shut off. We do not charge more after hours, so there is no advantage in guessing wrong in either direction.
If water is coming from the tank body itself, yes — the liner has failed and it will get worse rather than better. If it is dripping from a fitting, it is a repair that can usually wait until morning.
No. A corroded glass-lined steel tank cannot be patched, sealed or welded. Anyone offering to is selling you a few more weeks. Fittings, valves and connections are all repairable; the tank itself is not.
Close the cold inlet valve on top of the tank, then kill the heat: the control dial to OFF on gas, or the breaker on electric. Do not open the drain valve unless water is actively spreading — old plastic drain valves break.
No diagnostic fee, no trip charge, and a flat-rate price in writing before anything starts. If it is no hot water today, calling is faster than the form.
A real diagnosis and a flat-rate price in writing, anywhere in Portland, at no cost.