Water Heater Leaking from the Bottom: Causes and Fixes
A puddle under your water heater has a few usual suspects. Here's how to identify the cause and what each one costs to fix.
First: find exactly where the water is coming from
Dry the area around the heater completely, then watch. Water appearing at the drain valve (the small spigot near the base) is a different problem — and a different fix — than water seeping from under the tank itself or running down the tank's side. This five-minute check determines everything that follows.
Cause 1: Leaking drain valve (fixable)
The drain valve's washer hardens and cracks over years of heat cycles. If the drip is clearly from the valve spout, replacement is a quick job — usually under $250 in Austin — and your tank is fine.
Cause 2: Condensation (not a leak at all)
When cold groundwater enters a warm tank in humid weather, the tank sweats. Droplets form on the cold exterior and run down to the base, mimicking a leak. If the 'leak' appears after heavy hot-water use and stops on its own, suspect condensation — a technician can confirm in one visit.
Cause 3: Tank rust-through (replacement needed)
Water seeping from the base seam or from under the tank — with no valve nearby — means the steel tank has corroded through. This is the end of the road: the glass lining failed long ago, the anode rod is gone, and patching is not a real option. Budget $1,200–$2,400 for a code-compliant replacement in Austin.
Cause 4: Leaking from above, pooling below
Water from a failed T&P valve, inlet fitting, or supply line runs down the tank's side and pools at the base, looking like a bottom leak. Trace the wet trail upward — if the tank body is dry and the top is wet, the fix is at the top, not the bottom.
What a bottom leak costs to address
Drain valve replacement: $180–$300. Condensation diagnosis: a service call. Full tank replacement for rust-through: $1,200–$2,400 installed, including permit, expansion tank, pan, and haul-away. We quote the right fix after diagnosing — never before.
Related Services
We serve homes and businesses across Austin and Travis County — including 78731 — Northwest Hills and 78729 — Jollyville.
Frequently Asked Questions
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