“No hot water” is one symptom with about seven different causes behind it, ranging from a two-minute fix to a tank that’s finished. Working through them in order tells you which one you’re dealing with before you call anyone.
1. The pilot light is out (gas)
Look through the sight glass at the base of the tank. No flame means no heat. Relight it following the instructions on the label. If it lights but won’t stay lit once you release the control knob, that’s the thermocouple — a cheap part and a common failure.
2. The breaker has tripped (electric)
Check your panel. Reset it once. If it trips again immediately, stop — that’s a short in an element or thermostat, not a nuisance trip, and repeatedly resetting it is a fire risk.
3. A failed heating element (electric)
Most electric tanks have two elements. If the lower one fails, you’ll get a small amount of hot water that runs out fast. If the upper one fails, you’ll get none at all. Either is a routine, affordable repair.
4. A failed thermostat
Either the water is stone cold, or it’s scalding with no control in between. Thermostats are often replaced alongside an element since the labour overlaps.
5. Sediment build-up
If you’re getting less hot water than you used to and hearing rumbling or popping from the tank, sediment has layered across the bottom. In a gas unit it insulates the water from the burner; in an electric unit it buries the lower element. This is what hard water does to a tank that’s never been flushed — and it’s the most common cause we see in the San Gabriel Valley. Read more on what hard water does to plumbing here.
6. The dip tube has failed
The dip tube carries incoming cold water to the bottom of the tank. When it cracks, cold water mixes at the top and goes straight out to your taps. Symptom: lukewarm water that never gets properly hot, and a much shorter supply than usual.
7. The tank itself has failed
Water pooling at the base of the tank — not at a fitting, not from the discharge pipe, but from the body — means the steel shell has corroded through. There is no repair for this. Anyone who offers you one is not being straight with you.
What you can safely do yourself
Relighting a pilot, resetting a breaker once, and checking the thermostat setting. That’s the list. Anything involving opening the tank, working on gas, or touching electrical connections should go to a licensed plumber — and if you smell gas at any point, leave and call from outside.
Repair or replace?
The short version: under six years old, repair almost always wins. Past ten, and especially with sediment or rust in the hot water, put the repair money toward a replacement instead. Our cost guide breaks down both sides.
Get it diagnosed
We handle water heater repair across San Dimas, La Verne, Pomona and Glendora, usually same day. Call (949) 355-5640.
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