Short answerOn a gas water heater, no hot water usually means the pilot is out, the thermocouple has failed, or the gas control valve has locked out; check the status light and relight per the label. On an electric tank, check the breaker and press the red high-limit reset behind the upper panel. Lukewarm water that runs out fast points to a failed element or broken dip tube.
First: is it no hot water, or not enough?
These are different problems. No hot water at all, every tap, means the heater is not firing or not powered. Hot water that turns lukewarm after a short shower, or that was fine yesterday and is barely warm today, means the heater is producing some heat but not enough: one of two elements on an electric tank, a broken dip tube, or a tank so full of sediment that the burner cannot get heat through it. Run the kitchen hot tap for two minutes and note what you get before you go to the basement.
Also check the obvious: a 40-gallon atmospheric tank in a Garden City ranch that just supplied back-to-back showers, a load of laundry and the dishwasher is simply empty and needs 30 to 45 minutes to recover. That is not a fault.
The safety rule before anything else
If you smell gas near the water heater, do not touch the controls, do not flip light switches, leave the house, and call DTE Energy at 800-947-5000 and then 911 from outside. If the carbon monoxide alarm sounds, everyone out first. A water heater flue that has rusted through or come apart at the draft hood, which we find regularly on 15-year-old tanks in Michigan basements, can put CO into the house, and that matters far more than a cold shower.
Gas water heater: the control and the pilot
Most gas tanks installed since the mid-2000s have an electronic gas control valve with a small status LED near the knob. A blinking pattern is a fault code; the legend is on the sticker next to it. No light at all usually means the pilot is out and the thermopile is not generating power. Older tanks have a simpler gas valve with a knob marked Off, Pilot and On and a red or black ignition button.
To relight, follow the label on your tank exactly. The general sequence: turn the knob to Off and wait five minutes for any gas to clear; turn it to Pilot; press and hold the knob or the pilot button while clicking the igniter until the pilot lights (you can see it through the sight glass at the bottom); keep holding for 30 to 60 seconds; release and turn to On. If the pilot lights and then goes out when you let go, the thermocouple or thermopile is weak. If it will not light at all, the pilot orifice may be clogged, or gas is not reaching the tank.
A pilot that goes out repeatedly over days or weeks has a cause: a drafty basement, a flame-arrestor screen at the base of the tank clogged with lint and dust (very common in tanks sharing a room with the dryer), or a thermocouple on its way out. Our guide on a water heater pilot light that won't stay lit covers each of those.
If the pilot is lit but the water is still cold. If the pilot is on and the main burner never fires, turn the thermostat dial up and listen for the burner. If nothing happens, the gas valve's thermostat has failed, or the tank's high-limit (ECO) has tripped. On older valves the ECO is a one-time thermal fuse and the valve has to be replaced. On the electronic valves it is a resettable fault; the light will blink the code. Either way this is a water heater repair call, and on a tank past 10 years old, replacing the gas valve is a conversation about whether the tank is worth it.
If the burner fires but roars, rumbles or pops, the bottom of the tank is covered in sediment. Ypsilanti and Ann Arbor water is moderately hard, and a tank that has never been flushed builds an inch or more of scale in a decade. The burner heats the sediment, water trapped under it boils, and you hear it. Recovery slows, the bottom of the tank overheats, and the tank fails early. A flush helps if it is caught in time; see water heater maintenance, flush and anode.
Electric water heater: breaker and reset
An electric tank runs on a 30-amp two-pole breaker. Flip it fully off and back on. Then remove the upper access panel on the side of the tank (power off at the breaker first), fold back the insulation, and look for a red button on the upper thermostat. That is the high-limit reset. If it has tripped, pressing it firmly will click it back in. A reset that trips once can be a fluke. A reset that trips again within a day means an element is shorted to ground or a thermostat is stuck closed and overheating the tank; do not keep resetting it.
If the breaker and reset are fine and the water is cold, one or both elements has failed, which a tech confirms with an ohmmeter in a couple of minutes. The upper element heats first; if it fails, you get no hot water at all. If the lower fails, you get a short burst of hot water that goes lukewarm. Elements are inexpensive and replaceable, but a tank that is 12-plus years old with a failed element often has a corroded anode and a tank bottom that is next.
The dip tube and the mixing problem
A water heater that suddenly delivers lukewarm water at every tap, with the burner or elements working fine, may have a broken dip tube. The dip tube is a plastic pipe that carries incoming cold water to the bottom of the tank; when it cracks or breaks off near the top, cold water mixes straight into the hot outlet. Tanks from the mid-1990s had a notorious batch of these, but any tank can suffer it. A tech can pull the cold inlet nipple and check in a few minutes. Small white plastic bits in the faucet aerators are the giveaway.
A failed shower mixing valve or a single-handle faucet cartridge letting cold cross into the hot line produces the same lukewarm symptom house-wide. If the water heater outlet pipe is hot to the touch but the taps are lukewarm, suspect a crossover somewhere in the plumbing rather than the tank.
Signs the tank is done
- Water around the base that is not from the T&P valve or a fitting. A tank that is leaking from the shell has failed, and no part fixes it.
- Rusty or brown hot water, with clear cold water, on a tank past 10 years.
- A burner compartment with heavy rust flakes or a flame that burns yellow and lazy.
- More than one repair in the last two years on a tank over 12 years old.
Most 40- and 50-gallon atmospheric gas tanks in Washtenaw and Wayne County last 10 to 15 years; electrics run a bit longer. Water heater lifespan and replacement signs goes through the full checklist.
When to stop and call
If the pilot will not stay lit after two careful attempts, if the electric reset trips twice, if the gas valve shows a code you cannot clear, or if there is any water on the floor from the tank itself, call. We do water heater repair and water heater installation 24 hours a day, and most no-hot-water calls are finished the same visit because thermocouples, elements and thermostats are on the truck. A tank that has failed usually gets replaced the same day or the next morning.