How to Fix a Leaking Water Heater
Where the leak is determines whether it’s a $30 fix or a $2,000 replacement.
TL;DR
Water heater leaks come from 5 places, each with different fix and cost. Top connections: easy DIY ($10). Drain valve: easy DIY ($15). T&P relief valve: replace ($25). Cold/hot supply lines: replace ($12). Tank bottom: REPLACEMENT — not repairable ($1,800–$2,500).
What’s in this guide
- Locate the leak source
- Top fittings fix
- T&P valve fix
- Drain valve fix
- Tank bottom = replacement
Water on the floor near your water heater is alarming, but the location of the leak tells you whether you’re looking at a $10 fix or a $2,500 replacement. Here’s how to diagnose accurately in 15 minutes.
Tools & Materials You’ll Need
Tools
- Towel
- Flashlight
- Adjustable wrench
- Voltage tester (electric heaters)
Materials
- Replacement T&P valve if needed ($25)
- Replacement drain valve ($15)
- Plumber’s tape (PTFE)
Step-by-Step Instructions
First: Confirm It’s the Water Heater
Sometimes water at the heater base is from a different source — overhead pipe leak dripping, condensation from cold-water pipe, or AC drain pan overflow. Dry the heater and floor completely, then watch for 30 minutes. Identify exactly WHERE water reappears.
Inspect Top Connections
Look at the cold inlet and hot outlet at the top of the tank. Wet fittings or visible drips at the connections = loose fitting or worn supply line. Tighten gently. If still leaking, replace supply lines (braided stainless, $12).
Check the T&P Relief Valve
On the side or top of the tank, the T&P (Temperature and Pressure relief) valve has a discharge tube going down to the floor or a drain. If water drips from this tube, the valve is doing its job — but it shouldn’t happen routinely. Causes: high water pressure (above 80 PSI), thermal expansion (no expansion tank), or failed T&P. Test by lifting the valve’s small handle briefly — should release water then reseat.
Inspect the Drain Valve
At the bottom of the tank, the drain valve looks like a hose bib. If it’s dripping, the valve’s rubber washer has failed. Brass valves: replace washer or whole valve ($15). Plastic valves: replace whole valve (don’t repair).
Check Tank Bottom (Critical)
If water is pooling on the floor and you can’t trace it to top fittings or T&P discharge, the tank itself is leaking. This means corrosion through the tank wall — not repairable. The tank must be replaced.
Annual inspection catches most leak-causing issues before they fail catastrophically. We include a free 12-point inspection with any LA water heater service. The most common problem we find: a slow-leaking T&P valve that homeowners haven’t noticed because the discharge tube goes to a drain pan or floor drain. Test your T&P annually by lifting the handle briefly.
A leaking tank means imminent failure
A water heater tank that’s leaking from the bottom can rupture catastrophically (fully releasing 50 gallons in seconds). If you have a tank-wall leak, shut off the cold supply, drain the tank, and schedule replacement immediately.
Real Scenarios from Our LA Service Calls
Caught a tank-wall leak before catastrophic failure
Homeowner saw a small puddle near the heater base. Diagnosis: tank corrosion at the bottom seam, slow seepage. Drained the tank, scheduled replacement for next morning. By the time we returned, the small leak had become a 1/2-cup-per-hour drip — would have ruptured fully within days. Replaced with new high-efficiency 50-gallon. Total: $2,150 with permit.
When to Call a Plumber Instead
DIY isn’t always the right call. Bring in a licensed plumber if any of these apply:
- Tank-bottom leak (replacement required)
- You can’t locate the leak source
- Multiple leak points
- Heater is over 10 years old (consider replacement vs repair)
- You’re uncomfortable working with gas connections
Frequently Asked Questions
How long does a water heater last in LA?
8–10 years for builder-grade tanks in hard SFV water without flushing. 12–15 years for quality brand with annual maintenance. Coastal LA: similar with annual anode inspection.
Can a leaking T&P valve be ignored?
No. T&P leaks indicate one of three issues: high pressure (dangerous), thermal expansion (expensive on bills), or failed valve (immediate replacement). Address quickly.
Is a small leak going to get worse?
Tank-wall leaks: always. Connection leaks: only if not addressed. T&P leaks: only if root cause not fixed.
Should I drain my heater if it’s leaking?
For tank-wall leaks: yes, immediately. Reduces the volume of water that can escape. For other leak types: depends on the specific leak — sometimes yes, sometimes no.
Will my home insurance cover water damage from a leaking heater?
Usually yes for damage caused by the leak. Usually NOT for the heater replacement itself. Document everything and call insurance promptly.
Need professional help in Los Angeles?
Same-day service. Flat-fee pricing. No surprise add-ons.
Call (818) 938-8660
