Water Heater Leaking or Burst? Here's the Order

Shut it down, in this order

The sequence matters. Cutting the water without cutting the power can leave heating elements energized in an empty tank, which destroys them in minutes. Power, then water. In that order.

1. Kill the power or the gas. Electric: switch off the double-pole breaker labeled for the water heater. Gas: turn the control dial on the front of the unit to "off" or "pilot," then close the gas shutoff valve on the supply line.
2. Close the cold-water inlet valve. It sits on top of the tank, on the pipe coming in, usually the one with a blue handle or no marking at all rather than the hot outlet. Turn a round handle clockwise until it stops, or rotate a lever a quarter turn so it sits across the pipe. If that valve is seized or missing, close the whole-house shutoff instead. There is a walkthrough of where that lives in our burst pipe guide.
3. Relieve the pressure. Open a hot-water faucet somewhere in the house. This lets air into the system and slows the flow out of the leak.
4. Photograph it before you move anything. The unit, the data plate with the model and serial number, the puddle, the wet drywall behind and beside it, and a wide shot of the room. Then a slow video in which you say the date and what you are seeing.
5. Get the water off the floor. Wet/dry vacuum, squeegee, towels. Move boxes, paint cans, and anything cardboard out of the garage or closet. A water heater failure in a Florida garage usually ruins whatever was stored on the floor long before it ruins the building. Cardboard goes first.
6. Drain the tank if it is safe to do so. Attach a garden hose to the drain valve at the bottom and run it outside or to a floor drain. This is optional and only worth doing if the tank is still holding water and you can do it without contact with hot water. If in doubt, leave it for the plumber.
7. Call a licensed plumbing contractor. In Florida, plumbing contractors are licensed under Chapter 489 of the Florida Statutes through the Department of Business and Professional Regulation, and you can check any license number on the DBPR site before work starts.

Where is the water heater leaking from?

This is the question that decides whether you are buying a $30 part or a new appliance. You can usually answer it yourself in two minutes. Dry the outside of the tank completely, then watch where the water comes back.

Why Florida water heaters die early

HomeGuide's 2026 cost guidance is that tank water heaters last 8 to 15 years, and the practical planning number is 10. Florida pushes units toward the short end of that range for four reasons that stack on top of each other.

• Hard water. Much of Florida's supply is drawn from limestone aquifers and carries a heavy mineral load. Those minerals drop out of solution as the water heats and settle on the bottom of the tank, where they insulate the steel from the water, drive local overheating, and accelerate corrosion. That layer is also what makes an aging heater rumble or pop when it fires, which is the one warning sign most households actually get and almost nobody acts on, because a noise that has been in the garage for two years stops registering as a noise at all.
• Hot installation locations. Florida units usually live in an uninsulated garage or an interior closet, not a cool basement. Higher ambient temperature means the unit cycles differently, and the materials around it are the first things the water finds: the drywall bottom plate, the garage door track, whatever is stacked on the floor.
• A spent anode rod nobody checked. The sacrificial anode is a consumable that protects the tank lining by corroding instead of it. When it is gone, the tank starts corroding. Almost nobody inspects it, which is why so many failures feel like they came out of nowhere.
• Slab construction with no drain. In a house with no basement and no floor drain near the unit, there is nowhere for the water to go except across the slab and into whatever is next to it. A garage slab is poured to fall toward the overhead door, which sounds like good news until the water reaches a threshold or a settled spot, changes its mind, and runs under the door into the hallway instead.

If your unit is past ten years, has a rust-streaked jacket, or is already weeping at the base, the calculation has shifted. A planned replacement happens on a weekday, at a normal rate, with the floor dry. An unplanned one happens on a Sunday night with an emergency call-out fee on top.

What the water does while you sleep

A tank failure is not one 50-gallon event. As long as that cold-water inlet valve is open, the supply line keeps pushing water into a tank that cannot hold it, so the tank empties, and refills, and empties again, at whatever pressure the street is running that night, for as long as it takes somebody to notice. Overnight, that is hours of continuous flow at line pressure. Which is why so many of these losses get discovered in the morning rather than as they happen, and why the phrase people use is that the water heater flooded the house, not that it leaked.

The water then behaves like any other clean-water loss, and the clock behaves the same way. The EPA's guidance is that mold can grow on wood, drywall, carpet and furniture if they remain wet for more than 24 hours, and that anything that cannot be cleaned and dried within roughly 24 to 48 hours should be discarded. There is a full timeline in how long until mold grows after water damage.

Where the water actually goes in a Florida house:

• Up the drywall. Gypsum wicks moisture upward from the bottom plate. A wall that reads dry at eye level can be soaked to 18 inches, and the paper facing is exactly the food source mold prefers.
• Under the wall, into the next room. Water follows the slab, not the floor plan. A garage heater failure routinely wets the adjoining bedroom or hall carpet before anyone opens the garage door.
• Into base cabinets and their toe kicks, if the unit is in a laundry or utility closet. Particle board swells and does not come back.
• Under laminate, vinyl plank and engineered wood. These trap water against the subfloor and hide it. Swollen seams and a soft spot underfoot are the giveaways.
• Into the slab itself. Concrete absorbs moisture and releases it slowly for weeks, which is why a room can keep feeling humid long after the visible water is gone.

Category matters too. Water straight out of a heater tank starts as Category 1 clean water under the IICRC S500 standard, which is the cheapest and most recoverable class. But categories degrade with time. Clean water sitting in a warm house picks up soil and bacteria and gets reclassified upward, and the price moves with it. That is the strongest argument for calling someone at hour one instead of hour thirty.

Repair, replace, and what the damage costs

Two separate bills, and people routinely confuse them. The appliance is one line. The building is another, usually larger, line. These are published national market statistics. Useful for sanity-checking a number someone gives you, useless as a quote for your house.

Making the next one a nuisance instead of a disaster

Every water heater eventually fails. The only question you get to influence is whether it fails into a drain pan or into your hallway.

• A drain pan with a piped discharge. A metal or heavy plastic pan under the unit, plumbed to somewhere water can safely go, converts a slow leak into a puddle you notice instead of a floor you replace. A pan with no outlet is only worth so much. It catches drips, and then it overflows.
• A leak sensor. A battery water alarm costs very little and screams when the pan gets wet. A Wi-Fi sensor texts you, which matters more, because these failures like to happen while you are at work or away for the weekend.
• An automatic shutoff valve. A sensor tied to a motorized valve on the supply line closes the water when it detects a leak. This is the only measure on this list that works when nobody is home, which counts for more in Florida than in most states, given how many houses here sit empty for weeks at a stretch while the owners are somewhere cooler.
• Annual flush and anode check. Draining a few gallons off the bottom once a year clears sediment. Ask your plumber to check the anode rod while they are there. Replacing a $40 rod is cheaper than replacing a tank.
• Test the T&P valve periodically. Lifting the lever briefly confirms the valve is not seized, and a seized relief valve is a genuine safety hazard rather than a maintenance nicety. If you are not comfortable doing it, add it to the list for your next plumbing visit.
• Check your water pressure. Residential plumbing is generally built around a maximum of about 80 psi. High incoming pressure shortens the life of every valve, fitting and appliance in the house at once, and a pressure-reducing valve is a one-time fix.
• Know the age of your unit. The manufacture date is usually encoded in the serial number on the data plate. Photograph the plate now and put a reminder in your calendar for year eight.

On coverage: we are not licensed to advise you on your policy, and we will not try. Report the loss to your carrier factually and promptly, because your policy sets the notice deadline, and keep the failed unit or its data plate rather than letting the installer haul it away unphotographed. For general background, see does homeowners insurance cover water damage and confirm anything specific with your own licensed agent.

Common questions

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Keep reading

• House flooded? What to do in the first 24 hours. The full emergency checklist.
• Burst pipe water damage. The other supply-side failure, and where your main shutoff is.
• How long until mold grows. The 24 to 48 hour window, explained.
• What water damage restoration costs in Florida. The published ranges, with sources.
• How to choose a restoration company. Credentials, red flags, what to get in writing.
• All water damage guides