Water Heater Emergencies: Leaks, No Hot Water, and Safety
A leak from the tank body means the tank has corroded through and needs replacement, not repair. Shut off the water supply and the gas or breaker. No hot water alone is uncomfortable, not dangerous, and can wait for standard rates. A gas smell means leave the building first.
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Sort the problem by urgency
Water heater complaints span an enormous range of urgency, and knowing which one you have determines whether you pay the after-hours premium.
- Gas smell: evacuate and call the gas utility from outside. Everything else waits
- Tank leaking steadily: urgent, because it will not stop and typically accelerates
- T&P valve discharging: urgent, since it signals dangerous temperature or pressure
- Scalding hot water: urgent, a failed thermostat can deliver water hot enough to burn in seconds
- No hot water at all: uncomfortable, not dangerous. Schedule at standard rates
- Rumbling or popping: not urgent, but a signal the tank is scaling and nearing end of life
Shutting a water heater down safely
If the heater is leaking, shutting it down correctly limits damage and prevents an electric unit from destroying its elements by heating an empty tank.
Cut the energy source
For electric, switch off the dedicated breaker. For gas, turn the control knob to OFF or PILOT. Do this before touching the water.
Close the cold water inlet
There is a valve on the cold line entering the top of the tank. Close it. This stops the tank refilling as it drains.
Relieve pressure
Open a hot water faucet somewhere in the house so the tank can drain without pulling a vacuum.
Drain if necessary
Attach a hose to the drain valve at the tank bottom and route it to a floor drain or outside. A 50-gallon tank takes a while.
Do not relight after a gas smell
If gas was ever part of the picture, the utility clears the building before anything is relit.
Repair or replace
The deciding factor is where the water is coming from. Leaks at fittings, the drain valve, or the T&P valve are repairable and often cheap. Water seeping from the tank body itself means the inner tank has corroded through, and there is no repair for that at any price.
Age is the other factor. A conventional tank at ten or more years with a significant failure is generally not worth repairing, since the rest of the unit is at the same point in its life. Below about seven years, component repair is usually the better economics.
The safety issues worth taking seriously
Two water heater hazards are genuinely dangerous rather than merely expensive.
The temperature and pressure relief valve is the device that prevents a tank from becoming a pressure vessel failure. If it discharges, something is wrong and needs diagnosis. It must never be capped, plugged, or have its discharge line blocked, and any plumber who suggests otherwise should not be in your house.
Scalding is the other. Water above 120°F causes burns quickly, and at 140°F it burns a child in seconds. A thermostat set high, or one that has failed, is a real injury risk in homes with children or elderly residents. 120°F is the standard recommendation.
Frequently asked questions
My water heater is leaking. Is it an emergency?
It is urgent rather than a middle-of-the-night call, unless the leak is heavy or the tank is somewhere that water will do real damage, such as an upstairs closet. Shut off the cold inlet and the energy source, drain the tank if you can, and schedule the replacement. A leaking tank does not repair itself and generally worsens.
How long should a water heater last?
Eight to twelve years for a conventional tank, fifteen to twenty for a maintained tankless. Hard water shortens both considerably. In very hard water regions without softening, tanks routinely fail at six to eight years, well inside what the warranty period suggests.
Can I replace a water heater myself?
It is legal in some jurisdictions and not others, and it involves gas or 240-volt electrical, venting, and code requirements including expansion tanks, seismic strapping in some states, and drain pans. Getting the venting wrong on a gas unit produces carbon monoxide. Most people are better served hiring this one, and many jurisdictions require a permit regardless.
What temperature should I set my water heater to?
120°F is the usual recommendation: hot enough to suppress bacterial growth in the tank, cool enough to reduce scald risk, and it slows scale accumulation compared to higher settings. Households with immunocompromised members sometimes run higher with anti-scald mixing valves at fixtures, which is worth discussing with a plumber.
Related guides
- When to Call an Emergency Plumber (and When to Wait)After-hours plumbing costs 1.5 to 2 times standard rates. Here is which problems justify it and which are cheaper to schedule.
- Suspected Gas Leak: Leave First, Call From OutsideThe one plumbing-adjacent emergency where investigating is the wrong move. What to do, in order, if you smell gas.
- Frozen Pipes: What to Do Before They BurstA frozen pipe has not necessarily failed yet. Thawing it correctly, and being ready at the shutoff, is what keeps it from becoming a burst pipe.
- Sewer Backup: What to Do Right NowRaw sewage indoors is a health hazard as well as a plumbing failure. What to do, what not to touch, and how to keep it from recurring.
Related services
- Emergency Water Heater Repair and ReplacementDiagnosis and repair of water heater failures, including leaking tanks, no hot water, pressure relief discharge, and emergency replacement.
- Tankless Water Heater ServiceDiagnosis, descaling, and repair of tankless water heaters, including error code troubleshooting and flow sensor issues.
- Emergency Gas Line RepairEmergency repair of leaking gas lines and connections serving water heaters, furnaces, and appliances, performed by licensed technicians.
Cost guides
- Slab Leak Repair CostWhat it costs to find and fix a leak under a concrete foundation, and when rerouting beats repairing in place.
- Whole-House Repiping CostWhat it costs to replace a home's supply piping, how PEX and copper compare, and the scope question that causes most disputes.
- How Much Does an Emergency Plumber Cost?What emergency plumbing actually costs, how after-hours premiums work, and which problems are cheaper to schedule for morning.
Common questions
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- What Emergency Plumbing Actually Costs, and WhyA plain breakdown of after-hours rates, call-out fees, and the four questions that change your invoice.
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