Water Heater Leaking? What to Do in the First 10 Minutes

Where is the water coming from?

Dry the outside of the tank with a towel and watch for a minute. Nearly every water heater leak comes from one of four places:

1. The top — inlet and outlet connections

Water on the top of the tank or running down the sides from above usually means a loose or corroded fitting where the hot and cold pipes connect, a failed dielectric union, or a leaking flex connector. This is a repair: tighten, re-thread or replace the fitting. Do not over-tighten; brittle old nipples snap.

2. The side — the temperature and pressure relief valve

The T&P valve sits on the side (or top) with a pipe running down toward the floor. If that pipe is dripping, the valve is either doing its job — venting because pressure or temperature is too high — or it has failed. Either way it is a repair call, and the fix may include a thermal expansion tank if your home has a check valve or pressure regulator on the main. Never plug or cap this pipe.

3. The bottom — the drain valve

A drip from the small spigot near the bottom is usually the drain valve itself: plastic valves crack, brass ones weep at the stem. Sometimes it is sediment holding the valve open. Repair, not replacement.

4. The tank body

Water seeping from under the jacket, rust streaks down the shell, or a puddle with no visible source above it means the inner tank has corroded through. There is no repair for a leaking tank. It needs replacement, and the sooner it is shut down the less water ends up on the floor.

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Repair or replace?

Symptom	Likely cause	Fix
Wet at top, fittings damp	Loose/corroded connection	Repair the fitting
Drip from side discharge pipe	T&P valve venting or failed	Replace valve; add expansion tank if needed
Drip at bottom spigot	Drain valve	Replace drain valve
Water from under the jacket, rust streaks	Tank corroded through	Replace water heater
Rusty hot water, rumbling, 10+ years old	Sediment and end of life	Plan replacement

Age settles a lot of borderline calls. A tank-type water heater in Massachusetts typically lasts 8 to 12 years; if yours is past ten and leaking anywhere, replacing it usually beats a repair that buys a few months. Check the serial-number date on the label if you are not sure how old it is.

How do you prevent the next leak?

• Flush the tank yearly. Sediment insulates the bottom of the tank, overheats the steel and shortens its life.
• Test the T&P valve annually. Lift the lever briefly; it should discharge and reseat. If it sticks or keeps dripping, replace it.
• Check the anode rod every 3 years. The sacrificial rod is what keeps the tank from rusting; when it is gone, the tank starts corroding.
• Add an expansion tank if your home has a pressure-reducing valve or backflow preventer — trapped thermal expansion is what wears out T&P valves and fittings.
• Put it in a drain pan with a line to a floor drain if the heater sits over a finished space or above the basement floor.
• Consider a leak alarm — a $20 sensor on the floor beside the tank is the cheapest insurance in the house.

If you are looking at a puddle right now, shut the valves and call (978) 317-1244 — Precision Plumbing Solutions replaces most standard tanks the same day across Lynnfield, the North Shore and Greater Boston. For the longer view, our guide to tank vs. tankless water heaters covers what to install next, and the water heater service page has the details.