A water heater leaking is one of the most common — and concerning — issues homeowners face. Even a small leak can quickly lead to water damage, mold growth, and costly repairs if it’s ignored. Understanding why your water heater is leaking can help you take fast action and potentially save your home from serious damage.

Below, we’ll break down the most common causes of a leaking water heater, what you should do right away, and when it’s time to call a professional.

Common reasons your water heater is leaking

1. Loose or damaged plumbing connections

Over time, the pipes connected to your water heater can loosen due to regular expansion and contraction from heating cycles. If a connection becomes loose or a fitting cracks, water may drip or pool around the unit.

What to look for:

• Water dripping from the top of the water heater

• Moisture around inlet or outlet pipes

In some cases, tightening or replacing a fitting can solve the issue — but leaks at connections should still be inspected to ensure there’s no underlying damage.

2. Faulty temperature and pressure relief (T&P) valve

The temperature and pressure relief valve is a critical safety component. If pressure inside the tank becomes too high, the valve releases water to prevent the tank from rupturing.

A water heater leaking from the T&P valve may indicate:

• Excessive water pressure

• A failing valve

• Overheating inside the tank

This is not a part to ignore — a malfunctioning T&P valve can become a serious safety hazard.

3. Corrosion inside the tank

Water heaters naturally corrode over time, especially as they age. Once corrosion eats through the tank lining, water will begin leaking from the bottom of the unit.

Important:

• Tank corrosion is not repairable

• Leaks from the tank itself usually mean replacement is necessary

If your water heater is more than 8–12 years old and leaking from the bottom, corrosion is often the cause.

4. Cracked or leaking drain valve

The drain valve at the bottom of your water heater allows the tank to be emptied for maintenance. Over time, this valve can crack, wear out, or fail to fully close.

Signs include:

• Slow dripping from the bottom of the tank

• Water collecting near the base

Replacing the drain valve can often stop the leak — if caught early.

5. Excessive water pressure

High water pressure puts extra stress on your plumbing system and your water heater. This stress can cause fittings, valves, and even the tank itself to fail prematurely.

If your water heater is leaking intermittently, pressure issues may be the culprit. A professional can test your home’s water pressure and recommend solutions such as a pressure-reducing valve or expansion tank.

What to do:

If you notice a water heater leak, take these steps immediately:

1. Turn off the power or gas to the water heater

2. Shut off the water supply to the unit

3. Avoid using hot water until the issue is diagnosed

4. Call a professional water heater specialist

Delaying repairs can turn a minor issue into major water damage.

Can a leaking water heater be repaired?

Whether your water heater can be repaired depends on the source of the leak:

• Loose fittings or valves — often repairable

• T&P valve issues — repairable but urgent

• Tank corrosion — replacement required

A professional inspection is the best way to determine the safest and most cost-effective solution.

When to replace a leaking water heater

You should strongly consider replacement if:

• The tank itself is leaking

• Your water heater is over 10 years old

• Repairs cost more than half the price of a new unit

• You’ve experienced repeated leaks

Replacing a failing unit early can help you avoid emergency breakdowns and property damage.

Need help with your water heater?

If you’re dealing with a water heater leaking, don’t wait until the problem gets worse. At #1 Water Heaters, we specialize in fast, reliable water heater repair and replacement.

Our experienced team can quickly identify the cause of the leak and help you decide whether repair or replacement is the best option for your home.

Call #1 Water Heaters today at (206) 920-3456 to protect your home and restore your hot water with confidence.

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