Water Heater Leaking From the Bottom in La Vernia or San Antonio: What to Do Now

First moves, in order

1. Close the cold supply. Turn the cold line's valve, just above the tank, clockwise until it stops, or give a lever handle a quarter turn. If it's stuck, close the house main; on well water, also kill the pump at its breaker.
2. Cut the heat. Electric: switch its breaker off. Gas or propane: if you smell gas, go straight to the box below and leave the building. If not, turn the control knob to Off, then close the gas shut-off beside the heater. A burner or element firing on a draining tank can ruin good parts.
3. Protect the floor. Pull boxes, rugs and cardboard out of the water and mop up. For a closet or attic heater, check nearby drywall and the ceiling below.
4. Drain only if it's safe. The water can scald, so give it a few hours to cool with the heat off. Then hook a garden hose to the bottom drain valve, run it outdoors below the valve's height, and open a hot faucet indoors so air can enter. Don't drain if the drain valve is the leak, if it's brittle plastic, or if you're unsure: with the supply shut, no new water feeds the leak.

Gas or propane heater? Read this

If the heater stood in water, or a leak flooded the burner compartment or gas control, leave it off. Gas water heater labels generally warn against using one after any part has been under water; have the gas control and burner checked before relighting. CPS Energy wants the area around these heaters kept clear of clutter and flammable materials, so move paint, fuel cans and cleaners away.

Five possible sources

Dry the tank and pipes, ring the base with paper towels, and recheck with a flashlight in half an hour. The first damp spot gives it away.

• Relief valve: the temperature and pressure valve near the top has a pipe running down toward the floor. Water there means the valve opened, because of high house pressure, hot water expanding with nowhere to go, an overheating thermostat or a worn seat. Never cap that pipe.
• Drain valve: a dripping spout usually means grit is holding it open; a wet stem points to a cracked body or washer.
• Fittings above: a loose connector or weeping shut-off on top can trickle down behind the insulation jacket, so a "bottom" leak may start high. In older homes, steel nipples on top of the tank can rust from the inside.
• Condensation: a gas flame makes water vapor that beads on a tank of cold water and drips onto the burner, sometimes hissing. It fades as the tank warms and is worst in winter. A puddle still growing hours later is something else.
• The tank: seepage under the jacket, rust at the base, or water in the burner chamber that isn't condensation means the steel has corroded through. No patch or sealant makes that safe.

Hard water and the tank floor

SAWS says the calcium carbonate that makes its Edwards and Trinity aquifer water hard is naturally occurring. Rural water and private wells can be mineral-heavy too. Heat drops those minerals on the tank floor. On gas heaters the crust keeps water off the steel, so the bottom runs hotter and the lining wears sooner; on electric ones it buries the lower element. Flushing on schedule and a new anode rod help; see hard water and softeners.

Fix the part or replace the heater?

Failed parts get replaced: relief and drain valves, connectors, the cold shut-off, a bad thermostat. When high house pressure or thermal expansion is opening the relief valve, an expansion tank or pressure-reducing valve fixes the cause (water pressure repair). A leaking tank body means a new heater, and on an older unit that already rumbles or runs rusty, new parts rarely pay. We quote both and you choose; see water heater repair, replacement or our bilingual boiler repair page.

La Vernia treats any heater replacement in town, gas or electric, as permit work. San Antonio's Limited Service and Repair permit covers a small like-for-like swap (same type and size, same spot); a new size or fuel, a move, new piping, or tank-to-tankless takes a general plumbing permit and Development Services inspections. The plumber doing the work pulls the permit.

Leaking water heater questions

Call now or book a visit

Water you can't stop, water reaching rooms or a ceiling, or a gushing relief valve: call at any hour and we send our on-call plumber right away. With the valve closed, the heat off and the drip contained, we'll book the repair at a time that suits you. We're on US-87 in La Vernia and work in Floresville, Adkins, St. Hedwig, Seguin, Schertz, Cibolo, Converse and east San Antonio (all areas).

Office hours 8 AM–11 PM daily · 24/7 emergency service