Find the handle or lever on the pipe running into the top of the tank. Turn it clockwise until it stops. This keeps more water from filling a leaking tank.
For electric units, flip the breaker labeled water heater. For gas, turn the dial on the front to Off. Never leave a leaking heater running.
Wipe the area dry and watch for a minute. Water at the drain valve near the floor may just need tightening. Water welling up from under the tank means the tank itself is done.
Pull boxes, laundry, and anything on the floor away from the puddle. Standing water near a gas line or electrical panel is a hazard.
Most San Antonio water heaters sit in a garage or a closet, and most of them fail the same way: the steel tank rusts from the inside out. Our hard water speeds that up. Minerals settle to the bottom, bake against the burner, and eat through the tank over the years. Once it leaks from the bottom seam, there's no patch for it. The tank gets replaced.
Not every puddle means a dead heater, though. A plumber will check the drain valve at the base, the cold and hot connections up top, and the temperature and pressure relief valve and its discharge pipe. Sometimes it's a fitting that backed off or a relief valve doing its job because pressure got too high. Those are fixable without a new unit, so it's worth having someone look before you assume the worst.
Treat it as urgent if water is spreading across the floor, if you smell gas, or if the heater sits above living space in a two-story home in places like Stone Oak or Alamo Heights. A slow drip you can catch in a pan can usually wait a few hours. A steady flow can flood a garage fast, so shut it down and call.
When we come out, we figure out if you've got a repair or a replacement, and we walk you through both before anything happens. We cover the whole area, from Southtown and Monte Vista out to Boerne, Helotes, and New Braunfels.
Describe what you're seeing to a real San Antonio plumber: call (210) 555-0134 or send the form. Free, no obligation.