Five patterns cover almost every water heater complaint: no hot water at all, a leak, a strange noise or smell, a pilot that will not stay lit, and water that never gets properly hot. Matching the symptom below to its branch points at the page with the full diagnosis and the sourced repair cost.
Hot Water Brief is an independent cost-research site. We are not a contractor and do not perform the work ourselves.
This page is a short router, not a full diagnostic guide. For the complete symptom-by-symptom breakdown, with a table of causes and safety flags for every fault, see Water Heater Problems: What Is Wrong and What Repairs Cost. What follows here is the quick version.
| Symptom | Usually means | Full detail |
|---|---|---|
| No hot water at all | Failed element, thermostat, pilot, or thermocouple | Water Heater Problems |
| Water heater is leaking | A fitting, a valve, or a corroded tank | Repair a Water Heater Leak |
| Rumbling noise or rotten egg smell | Sediment, or the anode rod | Anode Rod Replacement Cost |
| Pilot or burner will not stay lit | A failed thermocouple | Thermocouple Replacement Cost |
| Lukewarm, never hot | Thermostat setting or failure | Thermostat Replacement Cost |
| Gas smell, water near electrics, tank spraying | An emergency, not a diagnosis | Emergency Page |
No hot water at all almost always means the heat source stopped, not that the tank itself failed. On an electric tank that is usually a burned out upper element or a tripped high limit switch. On a gas tank it is usually a dead pilot, a bad thermocouple, or no gas reaching the burner.
Fixr's national repair guide, updated 29 August 2025, prices an electric element at $200 to $750, a thermostat at $100 to $250, and a gas thermocouple at $150 to $325. See Water Heater Problems for the full symptom table, or go straight to Element Replacement Cost, Thermostat Replacement Cost, or Thermocouple Replacement Cost.
It depends entirely on where the water is coming from. A leak at a fitting, the drain valve, or the pressure relief valve is usually repairable. A leak seeping from the tank body itself, with nothing dripping onto it from above, means the steel has corroded through and the unit gets replaced rather than repaired.
How to Repair a Water Heater Leak walks through each source, a fitting, the drain valve, the relief valve, or the tank itself, part by part, including a test for ruling out ordinary condensation. If water is reaching an outlet, a cord, or the electrical panel, or the tank is spraying rather than dripping, go straight to the emergency page for what to shut off first.
A rumbling or popping sound is almost always sediment settled on the floor of the tank, boiling underneath the layer as the unit heats. A rotten egg smell in the hot water only, not the cold, points at the anode rod, which converts naturally occurring sulfates into hydrogen sulfide gas as it protects the tank from corrosion.
UGA Cooperative Extension's Circular 858-8, reviewed 17 July 2026, notes most people can detect hydrogen sulfide at concentrations as low as 0.5 parts per million. Water Heater Anode Rod Replacement Cost covers the fix and the inspection schedule. For sediment noise, or rusty water instead of a smell, see Water Heater Problems.
A pilot that lights and then dies within seconds almost always means the thermocouple is no longer proving the flame, so the gas valve shuts itself off as designed. The other common causes are a dirty pilot orifice, a blocked flue, or low gas pressure, none of which a homeowner should test directly.
Water Heater Thermocouple Replacement Cost covers the part, the millivolt test a technician uses, and why a brand-new thermocouple can still fail if not seated correctly. Relighting a pilot once, following the label on the unit, is a reasonable step. Relighting it repeatedly is not; a gas smell means the emergency page, not more relighting.
Lukewarm water at every tap usually points at the thermostat, either its setting or a failed unit, rather than at a burned out element. On a tankless heater, the same complaint usually means scale inside the heat exchanger is cutting how much heat it can transfer into the water flowing through it.
Water Heater Thermostat Replacement Cost covers electric and gas pricing and how to tell a thermostat fault from an element fault, which can look identical at the tap. A hot-then-cold pattern instead of lukewarm-everywhere points to a failed lower element, covered on Water Heater Element Replacement Cost and in the full table on Water Heater Problems.
$450 is the national average for a storage tank repair, typically $150 to $750, with a low of $75 and a high of $2,000, per Fixr's cost guide updated 29 August 2025. A tankless repair averages $375, typically $100 to $650, per Fixr's separate tankless guide, published 31 January 2025.
| Unit | Typical range | Average |
|---|---|---|
| Storage tank | $150 to $750 | $450 |
| Tankless | $100 to $650 | $375 |
These are national ranges, not a quote for your job. Water Heater Repair Prices breaks the same data down by part. For a Rheem unit, Rheem Water Heater Repair covers its own error codes and warranty terms.
It is an emergency when something is actively escaping or dangerous, not simply broken. A gas smell, water reaching an outlet or the electrical panel, and a tank that has burst or is spraying all call for shutting off water and fuel and getting help, rather than working through which part failed first.
No hot water alone, with everything dry, is not one of those. The emergency page covers the shutoff order and when to leave the building instead of troubleshooting.
Every number on this page traces to a published, dated source. Deeper diagnosis and further citations for each symptom live on the pages linked throughout.
For the full picture, start at Water Heater Problems: What Is Wrong and What Repairs Cost, or Water Heater Repair Prices for cost by part.
Match the symptom above, no hot water, a leak, a smell or noise, a pilot, or lukewarm water, then follow the link. [Water Heater Problems](/problems/) covers all of these in one table if none quite fits.
It depends on the unit's age, what failed, and the part's cost against a new heater. [Water Heater Problems](/problems/) covers ENERGY STAR's guidance that a unit over about 10 years old is generally worth replacing before it fails.
$450 on average for a storage tank, typically $150 to $750, and $375 on average for tankless, typically $100 to $650, per Fixr's cost guides updated 29 August 2025 and 31 January 2025. [Water Heater Repair Prices](/guides/water-heater-repair-prices/) breaks that data down by part.
Almost always a thermocouple that is no longer proving the flame to the gas valve. [Water Heater Thermocouple Replacement Cost](/guides/water-heater-thermocouple-replacement-cost/) covers the part and its $150 to $325 typical range, per Fixr.
As soon as you smell gas, water reaches an outlet or the electrical panel, or the tank is spraying rather than dripping. The [emergency page](/emergency/) covers the shutoff order and when to leave the building instead.
Independent Research
Published ranges for tank and tankless replacement, the failures that justify a repair, and the ones that do not. Sourced, dated, and free to read.
