Water Heater Leaking? Here's What to Do Before the Plumber Arrives

Step 1: Shut Off Power and Fuel

This comes before anything else, including looking for the source of the leak.

Electric Water Heaters

Cut power at the breaker panel — don't just switch off at a wall switch if one exists, since breaker shutoff is the more reliable disconnect.

Gas Water Heaters

Turn the gas control valve, typically located near the bottom of the tank, to the 'off' position. This stops the burner from continuing to heat a tank that may be losing water.

Then Close the Cold Water Supply Valve

Located on top of the tank where the cold water line enters, closing this valve stops new water from entering a tank that's already leaking, which limits how much total water ends up on your floor.

Step 2: Identify Where the Leak Is Coming From

Where the water is coming from tells you almost everything about whether this is a simple repair or a full replacement.

Leaking From the Top: Fittings and Valves

A leak from the top of the tank — around the cold water inlet, hot water outlet, or the temperature and pressure relief valve — is often a loose fitting or a failing valve, both relatively straightforward, affordable repairs.

Leaking From the Tank Body Itself

If water is coming from the tank's actual metal body, rather than a fitting or valve, this almost always means internal corrosion has eaten completely through the steel. There's no repair for a hole in the tank itself — the tank needs replacement, and continuing to run it risks a much larger, sudden failure.

Leaking From the Bottom

Often the hardest to diagnose precisely without draining the tank, since it could be a drain valve issue (repairable) or the tank body itself failing at the seam (not repairable). A plumber can determine which during the visit.

Step 3: Limit Water Damage While You Wait

Move anything valuable off the floor near the water heater immediately — boxes, stored items, and anything electronic are especially vulnerable. If there's a floor drain nearby, use towels or a wet-vac to help direct water toward it rather than letting it spread across the whole basement. If the water heater sits in a drip pan (many do, particularly in finished basements per code requirements), check whether the pan's own drain line is clear and functioning, since a clogged pan drain defeats its entire purpose.

Repair vs. Replace: How We Decide On-Site

Age matters as much as the specific symptom. A water heater under 5-6 years old with a fitting or valve leak is almost always worth repairing — these are common, inexpensive fixes on a unit that otherwise has years of life left. A water heater past 8-10 years, especially one leaking from the tank body, is a clear replacement situation regardless of how the rest of the unit looks, since the tank itself has reached the end of its structural life.

Same-Day Replacement

If replacement is the right call, we can often complete it the same day if we're carrying a compatible unit on the truck or can source one quickly — ask when you call, since having a working water heater back the same evening matters a lot when you've got a household depending on hot water.

Why Water Heaters Fail in the First Place

Understanding the cause helps you gauge whether a repair or replacement is the more durable long-term choice. Internal corrosion is the most common cause of tank failure — the anode rod, a sacrificial component designed to corrode instead of the tank itself, eventually gets used up, after which the tank's own steel starts corroding. Sediment buildup at the bottom of the tank, especially in homes that never flush their water heater, accelerates this process and reduces efficiency well before an actual leak develops. High water pressure beyond what the tank and its fittings are rated for can also stress seams and connections over time, particularly relevant in parts of Arlington with older, sometimes inconsistently regulated municipal pressure.

Frequently Asked Questions