Why tanks leak
A storage water heater is a steel tank lined with glass, wrapped in insulation and an outer jacket. A sacrificial anode rod inside slowly corrodes so the tank does not. Once the anode is used up, the tank wall itself starts to corrode, and in a home on Brea's hard water the layer of sediment on the bottom speeds that along by trapping heat against the steel.
When the tank finally rusts through, water seeps out under the jacket and shows up at the base, often as a slow puddle that comes back no matter how often it is wiped. That leak only gets worse. Leaks from the fittings, valves and connectors around the tank are a different matter: those parts can be replaced without replacing the heater.
Reading the leak
| Where the water is | Likely source | Usual outcome |
|---|---|---|
| Under the jacket, around the base | Tank wall corroded through | Replace the heater |
| Dripping from the drain valve spout | Worn or loose drain valve | Replace the valve |
| From the relief valve or its pipe | High pressure, overheating or a worn valve | Find the cause, then repair |
| Pipes or connectors on top | Loose or corroded connector, nipple or shutoff | Replace the fitting |
| Puddle only after a cold start | Possible condensation on a gas unit | Have it checked before assuming a leak |
| Floor wet, heater dry | A nearby pipe, softener or drain line | Trace the real source |
Finding the source yourself, safely
With the water and heater off, a few minutes of looking can save a wasted visit.
- Dry everything.Wipe the tank, the fittings on top and the floor with a towel so fresh water stands out.
- Work top down.Check the hot and cold connectors, the shutoff valve and the relief valve first. Water runs down, so a top leak can look like a bottom leak.
- Check the drain valve.Look for drips at the spout near the bottom. Do not open it.
- Feel under the jacket edge.Carefully, since the tank may still be hot. Moisture under the base with dry fittings above usually means the tank.
- Photograph it.Take pictures of the leak and of the label with the model and serial number for the plumber.
What happens next
- IfThe tank body is leakingThenPlan on replacement. Keep the water off to the heater and ask for a written quote that includes straps, venting, permit and haul-away.
- IfA fitting or valve is leaking on a newer, sound tankThenA repair is usually reasonable. Ask what part failed and why.
- IfThe relief valve is leakingThenDo not plug it. Ask the plumber to test water pressure and the thermostat before swapping the valve.
- IfThe heater sits in an indoor closetThenMove belongings, put down towels and ask whether a drain pan and drain line can be added.
What to ask a plumber about a leak
- Where exactly is the water coming from, and how do you know?
- Is this tank repairable, or is the tank itself failing?
- If it needs replacing, what does the quote include beyond the heater?
- Will you check water pressure and whether an expansion tank is needed?
- What is your CSLB license number so I can check it at cslb.ca.gov?
Common questions
Can a leaking water heater tank be patched?
No. Once the tank wall has corroded through, sealants and patches do not hold under heat and pressure. The safe fix is a new heater.
Is it safe to keep using a slowly leaking water heater?
A tank leak tends to grow, sometimes suddenly. Keep the cold-water supply off and the heater off until a licensed plumber has looked at it.
Why is there water under my heater but the tank looks dry?
The water may come from a fitting on top running down the side, from a nearby pipe or appliance, or from condensation on a gas unit after a cold start. Dry everything and watch where it returns.
General information for Brea, not a quote or professional advice. In an emergency, call 911.