Water Heater Leaking? Here's What to Do (And What It Costs to Fix)

You walked downstairs and there's water on the floor around your water heater. Before you panic and start shopping for a new one — take a breath. Not every leak means replacement. Some are cheap fixes. Here's how to figure out which one you're dealing with.

Step 1: Shut Off the Water Supply

Find the cold water supply valve on top of your water heater and turn it clockwise (righty-tighty). If it's a gate valve (round handle), turn it all the way. If it's a ball valve (lever handle), turn it perpendicular to the pipe.

Can't find it or it won't turn? Shut off your home's main water supply instead. It's usually near the water meter where the line enters your house.

Step 2: Identify Where the Leak Is Coming From

This is the most important step. The location of the leak tells you everything about the repair.

Leak from the top connections

Water pooling on top of the unit or dripping from pipe connections at the top. This is usually a loose fitting, failed nipple, or bad flex connector. This is almost always repairable — and cheap.

Leak from the T&P (temperature & pressure) relief valve

The T&P valve is on the side of the tank, usually with a copper or CPVC discharge pipe running down to near the floor. If water is dripping or flowing from this pipe, the valve may be faulty — or your water pressure/temperature is too high. Either way, it needs attention.

Leak from the drain valve at the bottom

The small spigot near the bottom of the tank. Sometimes it's just not fully closed, or the washer has failed. Easy fix.

Leak from the bottom of the tank itself

Water seeping from the base of the tank, rust stains, or water pooling under the unit with no other identifiable source. This usually means internal tank corrosion and failure. The tank is done. No repair — replacement needed.

Step 3: If It's Gas — Check for Gas Smell

A leaking water heater that also smells like gas (rotten eggs) is a different emergency. If you smell gas:

1. Don't flip any switches or light anything
2. Open windows
3. Get everyone out of the house
4. Call PECO at 1-800-841-4141 from outside

What We See Most Often in Philadelphia

We've handled 19 water heater leak calls since early 2024. Here's the breakdown:

• About 40% were repairable — bad valve, loose connection, failed flex connector. Cost: $150–$320.
• About 60% needed replacement — internal tank failure, severe corrosion, or the unit was already 12+ years old and a repair would've been throwing money at a dying appliance.

The age of the unit is the biggest factor. If your water heater is under 8 years old and the leak is from a valve or connection — repair it. If it's over 10 years old and leaking from the tank — replace it. The repair vs replace guide breaks this down in detail.

Preventing Water Heater Leaks

• Annual inspection: Check connections, look for corrosion, test the T&P valve
• Expansion tank: Required by Philadelphia code on closed systems. Prevents excess pressure that causes leaks
• Drain pan: If your water heater is on an upper floor or near finished space, a drain pan catches small leaks before they cause water damage
• Know the age: If it's approaching 10 years, start planning for replacement on your timeline — not the water heater's

The Bottom Line

A leak doesn't automatically mean a new water heater. But if the tank itself is leaking, there's no patching it — replacement is the only option. Either way, act quickly. A small leak becomes a flooded basement fast, especially in Philadelphia basements where drainage isn't always great.