When there is no hot water anywhere in the house, the cause is nearly always the water heater: a tripped breaker or failed element on an electric unit, a pilot light or igniter that has gone out on a gas unit, or an error code on a tankless one. When only one tap is cold, the fault is in that tap or its valve, not the heater.
Start with the simple checks below, because many cost nothing. This page is a spoke of our guide to water heater repair, which covers parts, brands and prices in Los Angeles.
What are the first signs of a water heater going bad?
The first signs are hot water that runs out sooner than it used to, water that is only lukewarm, rumbling or popping from the tank, rust-coloured hot water, and a damp patch at the base. Any of them can appear weeks or months before the heater fails outright, and each points to a different part.
What each one usually means:
- Runs out fast: a failed lower element on an electric tank, a broken dip tube, or sediment taking up the space where hot water should be.
- Lukewarm only: a thermostat set low or failing, or one of two elements dead.
- Rumbling or popping: sediment, common where hard water is the norm. LADWP says minerals drop out of heated water and form sand-like deposits, and recommends flushing a heater at least once a year.
- Rusty hot water, cold water clear: the inside of the tank is corroding. A heater 10 to 15 years old, the usual life the U.S. Department of Energy gives for storage units, is near the end.
- Water at the base: see our page on how to repair water heater leakage.
Why is there no hot water anywhere in the house?
Check power or gas first. For an electric heater, look for a tripped breaker and press the reset button on the heater's thermostat cover only after the power is off. For a gas heater, see whether the pilot is lit or the display shows a code. If both are fine, the part that heats the water has probably failed.
A step-by-step check for each type:
Electric tank
- Switch the breaker off and on once. If it trips again straight away, stop. That points to a shorted element or wiring.
- Check the reset button on the thermostat, which needs the power off and the panel opened. If you are not comfortable doing that, leave it for a plumber or an electrician.
- If the breaker holds and the water is still cold, a failed element or thermostat is likely.
Gas tank
- Look for the pilot light through the window at the base, or the status light on newer models.
- If it is out, follow the relighting steps printed on the heater. If it will not stay lit, a worn thermocouple or igniter is the usual cause. See thermocouple replacement on a water heater and water heater pilot light repair.
- If you smell gas at any point, leave the building and call SoCalGas on 1-800-427-2200 from outside. Call 911 if you are in danger.
Tankless Look at the display for an error code and note it. Common causes are a blocked intake or exhaust, a failed flame sensor, a clogged filter screen or a scaled heat exchanger. Cold water that suddenly stops a tankless unit from firing can also mean the flow is too low for it to start. Give the plumber the code and the model.
Why is there no hot water at only one tap?
If only the kitchen sink, or only one shower, has no hot water, the heater is fine. The cause is a blocked aerator, a failed shower cartridge or mixing valve, a closed or failed stop valve under the sink, or a crossed supply line. These are cheaper faults than a water heater repair.
Try this order:
- Unscrew the aerator at the end of the faucet and look for grit. Hard water scale blocks the hot side first.
- Check the hot stop valve under the sink. If it is at a quarter turn, open it fully.
- Run the hot tap in another bathroom. If it works, the fault is local to the first fixture.
- For a shower, a worn cartridge or mixing valve is the usual cause, and the repair means opening the wall trim.
A washing machine that fills with cold water only has a different problem: see washing machine no hot water. For a shower that stays cold or goes cold halfway, see shower no hot water.
Why is my pilot light lit but I have no hot water?
A lit pilot with no hot water means the gas valve is not opening the main burner. Likely causes are a failing thermocouple, a worn gas control valve, a thermostat that is set too low or has failed, or a blocked burner. The pilot flame is small, and it cannot heat a tank.
A pilot that is lit but yellow or weak, or a heater that makes a soot smell, points to a venting or combustion problem. Switch the heater off and call a plumber. Do not run a gas heater that smells of exhaust, and do not work on gas piping yourself, because California requires a licensed plumber for gas piping work.
Many gas heaters also have a safety cut-off that shuts the burner if the tank overheats. If the heater has gone cold after being very hot, it needs checking and should not be reset repeatedly.
What to do next: is no hot water an emergency, and who do I call?
No hot water alone is usually urgent but not an emergency. It becomes one with a leak, a gas smell, scalding water, or someone vulnerable in the home. Call a plumber for the heater itself, an electrician only if a circuit or panel is at fault, and your landlord first if you rent.
In an apartment building the heater is often shared or on a central system, so a report to the manager in writing is the first step. See apartment building no hot water for what to say.
A boiler or combined heating system is less common in Los Angeles homes than a separate tank. If you have one, a plumber or heating contractor will need to look at the heating side as well as the hot water side.
If the water heater is dead, a repair is worth it while the tank is sound and under 10 to 15 years old. See water heater replacement cost for what a new one costs, including water heater installation, and emergency water heater repair if the situation cannot wait.
Set a thermostat to about 120 degrees once it is working. The U.S. Department of Energy gives that as the usual home setting, and hotter water raises scald risk.
What does it cost to fix no hot water?
Published prices for Southern California put a service call and diagnosis at about $75 to $150, a thermocouple, pilot or igniter repair at $175 to $400, and most standard tank repairs at $150 to $650. Tankless repairs run about $200 to $1,100. A tank that has failed is replaced, not repaired.
These are guide figures, checked in November 2026. The written quote is the real price. If you want a plumber to come and look, use the quote page and give the heater type, the brand and what you have already checked.
Common questions
How long does a plumber take to fix no hot water?
Many faults are fixed in one visit of one to two hours, because the plumber can carry common parts such as thermostats, elements and thermocouples. A part that has to be ordered, or a heater that has to be replaced, takes longer. The plumber can give you an estimate once they have seen the unit.
What should I ask before I hire someone to fix my no hot water problem?
Ask what the fault is and whether the tank is still worth repairing. Ask for the repair price and a replacement price in writing. Ask whether a permit applies, and who handles it. Ask about parts: whether they have the right one on hand for your brand and model.
Does someone need to be at the property?
Yes, or someone you trust. The plumber needs access to the heater, the water shut-off and, for an electric unit, the panel. In Los Angeles, a replacement needs a permit, and the property owner may have to sign it. Clear the area round the heater before the visit.
Why is there no hot water but the heating is working?
In most Los Angeles homes the heating and hot water are separate systems, so a working furnace tells you nothing about the water heater. Treat them as separate faults. If both run off one boiler, a plumber or heating contractor should look at it, because the cause may be a zone valve or the boiler itself.
Could hard water cause no hot water?
It can contribute. Scale on an element or in a tankless heat exchanger lowers output until the unit shuts down or the water goes lukewarm. LADWP reports average hardness from 147 to 279 mg/L across its zones. A yearly flush or descale slows the build-up.