Short answer
Two different faults hide behind one complaint. If there is no hot water anywhere, suspect a tripped breaker or high-limit switch on an electric heater, or a pilot or ignition failure on a gas one. If hot water runs out faster than it used to, the heater is working but its capacity is being lost, usually to sediment, a failed lower element, or a dip tube.
Those are two different problems and they lead to different repairs, so the useful thing to establish before calling is which one you have: none at all, or less than there was. On untreated well water, sediment accumulates faster than most people expect, which makes the second pattern common here well before a tank reaches the end of its nominal life.
First: which of the two problems do you have?
This single distinction eliminates most of the possible causes, and it takes thirty seconds. Run a hot tap and watch what happens.
Never any hot water, at any tap, for any length of time, means the heater is not heating. Hot water that is normal at first and then goes cold sooner than it used to means the heater is heating but not delivering its full tank. Hot water at some taps and not others is neither. That is a distribution problem, usually a mixing valve or a cartridge, not the heater at all.
| What you observe | What it usually means | Where to look first |
|---|---|---|
| No hot water at any tap | The heater has stopped heating | Breaker, high-limit reset, pilot or ignition |
| Hot then cold within a few minutes | Lower element failed, or heavy sediment | Electric elements, tank flush |
| Hot water runs out much sooner than it used to | Capacity lost to sediment or a broken dip tube | Tank age, flush history |
| Lukewarm everywhere, never hot | Thermostat setting, or crossed connection | Thermostat, mixing valve |
| Hot at one tap, cold at another | Fixture cartridge or mixing valve | That fixture, not the heater |
| Was fine, then failed right after a cold snap | Possible frozen or split line | Check for leaks before resetting anything |
What you can check yourself, in order
These are safe for a homeowner and they resolve a real share of no-hot-water calls. Stop at any point where you find water where it should not be.
- Look at the heater before you touch it. Check for water on the floor, on top of the tank, or around the base. If the tank itself is leaking, this is not a heating fault and resetting anything is the wrong move: shut the water and the power off.
- Check the breaker. For an electric heater, find its breaker at the panel. Switch it fully off and back on instead of just looking at it, because a tripped breaker does not always look different.
- Press the high-limit reset. Electric heaters have a red reset button behind an access panel on the upper thermostat. Press it once. If it trips again, stop: something is causing it and repeatedly resetting it is not the answer.
- For gas, check the pilot or the ignition. Look through the sight glass. A gas heater with no flame and no ignition attempt has usually lost its pilot or its thermocouple. Follow the relighting instructions on the tank's own label, and only those.
- Check the thermostat setting. Someone may have turned it down, or the unit may have been left in a vacation setting. On most tanks the target is around 120°F.
- Note the age. Find the serial number on the data plate: most manufacturers encode the build date in it. Past ten to twelve years, the answer to almost every fault is replacement instead of repair, and knowing that before you call changes the conversation.
When no hot water is urgent, not inconvenient
Most no-hot-water situations can wait until normal business hours, which usually costs less. Four cannot.
Water pooling under or around the tank means the tank may be failing, and a tank that lets go releases its full volume at once. A temperature and pressure relief valve that is discharging is a pressure problem, not a nuisance: turn the heater off. Any smell of gas is an evacuate-and-call-the-utility situation. And in freezing weather, no hot water alongside no cold water points at a frozen line, which is a different and more urgent problem than a failed heater.
What this looks like in Vermont specifically
Two local factors change how often this happens and why. Water chemistry across Chittenden and Franklin counties varies enormously between municipal supply and private wells, and a heater on untreated hard well water accumulates sediment far faster, which is the single most common reason a Vermont tank loses capacity years before it should.
The other is location. Vermont water heaters mostly live in basements, and a basement that runs cold puts a heat pump water heater into resistance backup and slows recovery on any tank. If a heater has always struggled in January and been fine in July, that is a clue about the room rather than the appliance.
What a contractor does on the visit
Expect the visit to establish three things: whether the heater is heating, whether it is holding what it heats, and whether the tank itself is sound. On an electric unit that means testing both elements and both thermostats and checking continuity instead of swapping parts. On a gas unit it means checking the thermocouple or igniter, the gas valve and the draft.
Ask for the finding before the quote. A failed element, thermostat or thermocouple on a tank under about eight years old is a repair worth making. The same fault on a twelve-year-old tank usually is not, and a contractor who explains which one you have is giving you the information you actually needed.
When it is a sizing question, not a fault
If your hot water works but there was never enough of it, such as a second shower that always runs cold or a tub that cannot be filled, the heater is not broken. That is a sizing question, and the checks are in the related article on not having enough hot water.
Common questions
Why do I have no hot water but the heater seems to be running?
On an electric heater this is the signature of a failed lower element: the upper element still heats the top of the tank, so you get a short burst of hot water and then cold, and the unit draws power the whole time. On a gas heater a burner that lights but cannot maintain temperature usually points at the thermostat or a heavily sedimented tank insulating the burner from the water. Either way the unit is consuming energy without delivering, which is why the bill can rise while the hot water falls.
Can I fix no hot water myself?
Sometimes. The safe checks are worth doing first: resetting the breaker, pressing the high-limit reset once, relighting a pilot following the label on the tank, and confirming the thermostat setting. Replacing an electric element is within reach of a confident homeowner provided the breaker is off and the tank is drained first. What you should not do is keep resetting a limit that trips repeatedly, or work on a gas train beyond relighting the pilot.
What happens if I ignore a water heater that only makes lukewarm water?
Usually it gets worse rather than dangerous, but there is one exception worth knowing. Water held below roughly 120°F for long periods is more hospitable to bacteria, including Legionella, which is why the recommended setting is a compromise between scald risk and that. More commonly the practical outcome is that the underlying fault, a failing element, a thick sediment layer, continues to develop until there is no hot water at all, on a day you did not choose.
How long should hot water last before it runs out?
Capacity matters more than gallons. It depends on the tank's first-hour rating, not its gallon capacity, but the useful measure is your own history: a heater that used to give two showers and now gives one has lost roughly half its usable capacity, and that is a fault regardless of what the specification says. Sudden loss over weeks points to an element or a dip tube. Gradual loss over years points to sediment.
How do I know if my water heater is leaking or just condensating?
Dry everything thoroughly, put down paper towel or newspaper around the base, and check it after a few hours of the heater running. Condensation appears during heating and disappears afterwards, and is most common on a new tank or in a humid basement. A genuine leak keeps producing water and usually leaves mineral staining or rust where it runs. Water emerging from the bottom seam of the tank itself is not condensation and is not repairable.
In a rental, is the landlord responsible for no hot water?
In Vermont, yes. The warranty of habitability at 9 V.S.A. § 4457 requires a landlord to maintain the facilities that supply hot water, and hot water is explicitly part of what makes a dwelling habitable. Report it in writing and record the date. Do not arrange a replacement yourself and seek reimbursement afterwards without advice: Vermont has specific procedures for when a landlord fails to act, and improvising one can put a tenancy at risk.
Why does my hot water run out faster than it used to?
The heater is heating, but it is losing capacity. Sediment, a failed lower element or a dip tube are the usual causes. On untreated well water, sediment builds faster than most people expect. So this pattern is common well before a tank reaches the end of its nominal life.