Water Heater Leaking from the Bottom: What to Do

A water heater leaking from the bottom of the tank is, in most cases, a failed tank. Tank failure is not repairable — once the steel tank corrodes through, the only fix is full replacement. The good news is that the warning signs usually give you time to plan a replacement rather than face an emergency.

This guide covers what to do in the first 10 minutes when you spot water at the base of the unit, how to tell tank failure from a fixable leak elsewhere, and what to expect when you call a plumber.

First 10 Minutes: Stop the Damage

If you see water around the base of the water heater:

Turn off the cold water supply to the heater. The shutoff valve is on the cold water line entering the top of the tank.
Shut off the power. Gas: turn the gas control knob to OFF. Electric: flip the breaker.
Open a hot water faucet in the house to relieve pressure in the lines.
Drain the tank if you can — connect a hose to the drain valve and run it to a floor drain or outside. A full tank holds 40-80 gallons; that is 320-650 pounds of water you do not want sitting in a failing tank.
Document with photos for your insurance.
Call a plumber. Our emergency line for severe leaks, normal scheduling for slow drips.

Where Is the Leak Actually Coming From?

Not every "leak at the bottom" is a failed tank. Check these first because they are fixable:

Drain valve. The plastic or brass drain valve at the bottom front of the tank often weeps or drips, especially after a flush. Replacement: $80-180.

T&P discharge tube. The pressure relief valve at the top of the tank discharges out a tube that ends near the floor. If water is dripping from the open end of that tube, the TPR valve is releasing — possibly because of overheating, thermal expansion without an expansion tank, or a stuck valve.

Supply line connections. Where the cold inlet and hot outlet connect at the top of the tank can leak — corroded flex lines, loose unions, failed dielectric nipples. Water then runs down the side of the tank and pools at the base, appearing to come from below.

Condensation. High-efficiency gas units produce acidic condensate that drains. If the condensate line is clogged or disconnected, water can pool. This is not a tank failure.

Expansion tank leak. The small expansion tank on the cold supply line can fail and drip water.

If you can confirm the leak source is one of these, you may be looking at a $100-450 repair rather than a $1,000-2,500 replacement.

When It Really Is the Tank

If the leak appears to come from the tank itself — water seeping from welds, water pooling under the unit with no visible upstream source, rust streaks running down the outside of the tank — the tank is failed.

Signs you are looking at tank failure:

Rust visible on the bottom of the unit
Hot water has been discolored for weeks
Tank is past 8 years old (gas) or 10 years old (electric)
Loud rumbling/popping during heating cycle
Water is consistently puddled regardless of recent use

There is no patch for a failed tank. Plumbing tape, sealant, and "epoxy fixes" sold online do not work on a pressurized steel tank with 120°F+ water. Replacement is the only option.

How Much Damage Can a Leaking Tank Do?

A small drip might give you days or weeks of warning. A sudden tank rupture releases 40-80 gallons in minutes — enough to:

Damage flooring across an entire room
Soak into baseboards and drywall
Reach the floor below in a multi-story home
Trip electrical hazards if it reaches outlets or wiring

Water damage restoration after a tank rupture commonly runs $3,000-15,000+. Catching the early warning signs (small drip, rust at the base) is the difference between a planned replacement and a major insurance claim.

What to Expect From a Replacement Call

When you call:

We confirm symptoms by phone and give you a price range
Most replacements can be done same-day or next-day depending on schedule
We bring the new unit, all fittings, expansion tank, and code-required components
Removal of old unit + install of new unit + flush + leak test typically takes 3-5 hours
Permit is pulled and inspection scheduled if your municipality requires it
Workmanship warranty (we offer 1 year) plus the manufacturer's tank warranty (typically 6 years)

See full water heater installation cost detail.

Should You Upgrade While Replacing?

Since the labor is the same to swap any tank with any other tank, this is a natural moment to think about:

Tank to tankless — see tankless vs. traditional. Added cost but lower lifetime cost.
Tank size up — if you have been running out of hot water, go from 40 to 50, 50 to 75.
Higher efficiency — newer high-efficiency tanks pay back over their lifespan.
Adding a recirculation system — instant hot water at remote fixtures.

We will walk through options on the quote.

Insurance Questions

Standard homeowners policies typically cover water damage caused by a sudden tank rupture (with deductible). They typically do not cover the replacement of the tank itself — that is normal wear and tear.

Document the date you discovered the leak, take photos, and call your insurance company before any water damage cleanup begins. Most policies require notification.

Service Area

Emergency and scheduled water heater replacement throughout Round Rock, Cedar Park, Pflugerville, Georgetown, and Hutto. 24/7 emergency response.