Close the cold water inlet valve on top of the tank, then cut the fuel: set the gas control knob to off and close the manual gas shutoff valve, or switch off the water heater breaker. If you smell gas, do none of that. Get everyone outside and call 911 from outside.
Read this before you go further. Hot Water Brief is an independent cost-research site. We are not a contractor, we do not perform the work ourselves, and we cannot send anyone out to you. This page is information you can act on while you make your own calls.
The order matters. Shutting the water first means the tank stops refilling itself, so whatever is on your floor has an end point. Cutting the fuel second removes the ignition and shock risk before anybody goes near the appliance with a bucket.
Do not open the tank drain valve on a leaking heater until the fuel is off and the water has had hours to cool. The Consumer Product Safety Commission records that most adults suffer third-degree burns from two seconds of contact with 150 degree water, six seconds at 140 degrees, and thirty seconds at 130 degrees. A tank that was running until a few minutes ago is sitting at or near its thermostat setting.
When you smell gas. A rotten egg odor near a gas water heater means you stop, take everyone out, and make the call from outside. Federal pipeline safety guidance is to leave the area and telephone 911 from a neighbor's house or another location well away from the leak.
There is no version of this where you investigate first. The reason is simple: the things you would normally reach for are ignition sources.
Carbon monoxide is the version of this you cannot smell. It has no odor and no color, and a gas water heater that is backdrafting can produce it. The Centers for Disease Control and Prevention lists headache, dizziness, weakness, nausea, vomiting, chest pain and altered mental status as the common symptoms, often described as flu-like, and says that if carbon monoxide poisoning is suspected you get outside first and then call 911.
Sometimes. Gas odor, water reaching electrics, and a tank that has burst or is spraying are genuine emergencies and should be treated that way. No hot water on its own, a small drip caught in a pan, or a pilot that keeps going out are annoying but usually survivable until normal working hours.
The useful question is not how bad it feels. It is whether something is escaping, and whether anything dangerous is in the path of it.
| What you are seeing | Treat it as | The basis for that |
|---|---|---|
| Smell of gas near the appliance | Leave the building, then call 911 and the gas utility from outside | PHMSA: leave the area and telephone 911 from well away from the leak |
| Water reaching outlets, cords or the electrical panel | Emergency, and do not step into the water | CDC: never turn power on or off, or use an electric appliance, while standing in water |
| Tank has burst or is spraying | Emergency, close the water supply if you can reach the valve without standing in water | The flow does not stop while the supply is open |
| Heater has been submerged in flood water | Do not operate it, controls must be replaced | CPSC: gas control valves, circuit breakers, GFCIs and fuses that have been under water must be replaced |
| Relief valve discharging repeatedly | Urgent, get a licensed plumber, do not cap the pipe | ICC: any discharge signals a water system fault, a heater fault or a failing valve |
| Headache, dizziness or nausea around a fuel-burning heater | Emergency, get outside then call 911 | CDC: those are common carbon monoxide symptoms |
| No hot water, and everything is dry | Not an emergency, book normal hours | Nothing is escaping and nothing is at risk |
| Slow drip caught in a pan or floor drain | Not an emergency, but dry the area within a day or two | EPA: drying within 24 to 48 hours normally prevents mold |
Source: PHMSA, Pipeline Leak Recognition and What to Do (accessed August 2026); CDC, Reentering Your Flooded Home and Carbon Monoxide Poisoning Basics (accessed August 2026); CPSC, Warning to Flood Victims (September 29, 1993, reissued February 5, 2024); ICC Building Safety Journal, May 13, 2019; EPA, A Brief Guide to Mold, Moisture and Your Home (updated February 18, 2026).
One caveat worth naming: an older person, an infant, or anyone whose health depends on warm water at home turns a no hot water call into a real problem faster than a dry basement suggests. That is a judgement call about the household, not about the appliance.
Stay out of it if it is anywhere near electricity. CDC guidance is not to enter standing water to reach the main power switch, and to call an electrician to do it instead. Never switch power on or off, or use an electric tool, while standing in water. Once it is safe, drying becomes the clock.
The EPA puts that clock at 24 to 48 hours: if wet or damp materials and areas are dried within that window after a leak or spill, in most cases mold will not grow. That is the reason to start moving water and air before anyone arrives, rather than after.
That last point is the one homeowners argue with most, and it is the one with the least room for argument. Silt and corrosion get inside the valve body where you cannot see them, and a control that fails later fails as a gas control. Replacement is a licensed professional's job.
Expect the hourly rate to climb. HomeGuide's 2026 figures put evening and weekend plumbing at $125 to $170 an hour, roughly 50 to 100 percent above standard rates, plus a $150 to $250 service fee outside business hours. Fixr, in January 2025, put standard plumber labor at $75 to $150 an hour.
| Line item | Standard hours | Urgent or after hours |
|---|---|---|
| Plumber labor per hour | $75 to $150, national average $90 (Fixr, January 2025) | $100 to $350 (HomeGuide, 2026) |
| Evening and weekend hourly | covered by the range above | $125 to $170, roughly 50 to 100 percent above standard (HomeGuide, 2026) |
| Call-out or trip charge | $50 to $200 transportation fee (Fixr, January 2025) | $200 to $300 emergency call-out flat fee (Fixr, January 2025), or a $150 to $250 out-of-hours service fee (HomeGuide, 2026) |
| Water heater repair, parts and labor | $150 to $750, national average $450 (Fixr, August 2025) | add $100 to $200 for urgent work (Fixr, August 2025) |
Source: Fixr, Cost to Hire a Plumber (updated January 30, 2025); Fixr, Water Heater Repair Cost (updated August 29, 2025); HomeGuide, How Much Does an Emergency Plumber Cost (2026).
Two things drive the spread. The first is when you call, because the surcharge is for the hour, not the fault. The second is whether the job turns out to be a repair or a replacement, since a split tank is not repaired at any price. Nobody here can quote you, and any number you are given on the phone before someone has looked at the appliance is a starting point rather than a price.
It is worth setting those numbers against what the water costs if it keeps running. The Insurance Information Institute, using ISO data covering 2018 to 2022, records water damage and freezing as the second most frequent cause of homeowners claims after wind and hail, at an average claim of $13,954. Against that, an after-hours surcharge is usually the smaller number.
Anything involving gas, live electrics, or a discharging relief valve. The International Code Council is blunt about that last one: any water discharge from a relief valve indicates a water distribution system problem, a water heater problem, or a valve that is malfunctioning. Capping the pipe to stop the drip creates a dangerous situation.
What is left for a homeowner is genuinely useful: close the water, cut the fuel if you can do it safely and dry, get people away from anything you can smell, and start drying the room. Everything past that point is licensed work, and on a gas appliance it is licensed work for a reason.
A repeat Rheem tankless code 13 is a combustion shutdown; leave the unit off and call a gas technician. If a Rinnai display shows 12, the code 12 guide lists the two checks an owner can make before calling.
Every figure on this page carries a named source and a date, listed below. Safety guidance is federal wherever federal guidance exists. Price ranges come from national cost guides with their publication dates attached, because a price with no date on it is not much use to anybody trying to judge a quote.
Where a source could not be found for a number, the number is not on the page.
Not on its own. If there is no leak, no gas odor and nothing wet near wiring, losing hot water is an inconvenience you can book for normal working hours. It becomes an emergency when water is escaping, when you smell gas, or when water reaches outlets, cords or the electrical panel.
No. The Consumer Product Safety Commission states that gas control valves, electric circuit breakers, GFCIs and fuses that have been under water must be replaced, that they are unfit for continued use even if they appear to function afterwards, and that they cannot be repaired. Have a licensed professional handle the replacement.
You can stop the flow, and that is the part a homeowner should do: close the cold water inlet valve, then cut the fuel. Beyond that, a leak from the tank body is corrosion, and a corroded tank gets replaced rather than patched. Fittings, the drain valve and the relief valve are licensed plumbing work.
HomeGuide's 2026 data puts evening and weekend plumbing at $125 to $170 an hour, roughly 50 to 100 percent above standard rates, plus a $150 to $250 out-of-hours service fee. Fixr's January 2025 figures put standard labor at $75 to $150 an hour with a $200 to $300 emergency call-out fee.
No. The International Code Council notes that the discharge pipe must end in an air gap with no threaded connection, valve or tee, precisely so it cannot be capped. Any discharge points to a water system problem, a heater problem or a failing valve, and all three need a licensed plumber.
No. Leave. Federal pipeline safety guidance is to leave the area and telephone 911 from a neighbor's house or another location well away from the leak, without using a phone or touching any electrical switch inside. Let the gas utility or the fire service make the appliance safe.
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.
