Water Heater Emergency Guide: Leaks, No Hot Water & Strange Noises

Your water heater just did something alarming. Maybe it’s leaking on the floor. Maybe there’s a strange banging noise. Maybe you turned on the shower and got nothing but cold water. Maybe you smell gas.

Don’t panic. Here’s exactly what to do for each situation, and when to call us.

Your Water Heater Is Leaking

How serious is it? It depends on where the leak is coming from.

Leak from the bottom of the tank

This is usually the most serious. It typically means the tank itself has corroded through. Internal rust and sediment buildup weaken the steel over time, and eventually the tank develops a crack or pinhole.

What to do:

1. Turn off the power. Gas: turn the gas valve to “OFF” (not just “pilot”). Electric: flip the breaker labeled for the water heater.
2. Turn off the cold water supply to the water heater. There’s a valve on the cold water pipe above the unit, turn it clockwise to close.
3. Attach a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open the valve to drain the tank and stop the flooding.
4. Call us at (603) 440-8113. A tank leak from the bottom almost always means replacement. We offer same-day water heater replacement in most cases.

DO NOT ignore a small drip. Tank leaks only get worse, never better. A slow drip today is a flooded basement next week.

Leak from the top (pipes or fittings)

This is often fixable. Leaks from the hot or cold water connections, the T&P valve, or pipe fittings above the tank are usually caused by loose connections, corroded fittings, or a failing T&P valve.

What to do:

1. If the leak is small, place a bucket underneath and call us for a repair appointment.
2. If it’s spraying or dripping fast, shut off the cold water supply above the tank.
3. Do NOT try to tighten connections while the system is hot and pressurized, you can burn yourself or crack a fitting.

Leak from the T&P (Temperature & Pressure Relief) valve

The T&P valve is the safety device on the side of your tank with a small discharge pipe pointing down. If it’s dripping or releasing water, the tank may be overheating or experiencing excessive pressure.

What to do:

1. Check the thermostat, it should be set to 120°F. If someone turned it up to 140°F or higher, that could cause the T&P to release.
2. Do NOT cap or plug the T&P valve. It’s a safety device that prevents the tank from exploding. Seriously.
3. Call us at (603) 440-8113 to inspect the valve and check for underlying issues.

No Hot Water

The most common emergency call we get. Here’s how to troubleshoot before calling.

Gas water heater, no hot water

1. Check the pilot light. Look through the small window at the bottom of the tank. If you don’t see a small blue flame, the pilot is out. Follow the relighting instructions on the label. If the pilot won’t stay lit after relighting, the thermocouple needs replacement, call us.
2. Check the gas valve on the front of the unit. It should be set to “ON” (not “OFF” or “PILOT”).
3. Check the thermostat dial. It should be at 120°F or the “warm” setting. If it was turned down accidentally, turn it back up and wait 30-60 minutes.
4. Smell for gas. If you smell rotten eggs near the water heater, do not attempt to relight the pilot. Leave the area and call your gas utility and then call us.

Electric water heater, no hot water

1. Check your breaker panel. Find the breaker labeled “Water Heater” and see if it’s tripped (in the middle position). Reset it once by flipping it fully off, then on.
2. If the breaker trips again immediately, do not keep resetting it. There’s an electrical fault, call us.
3. If the breaker was fine, the heating element or thermostat inside the tank has likely failed. This is a common repair that takes about an hour. Call us at (603) 440-8113.

Tankless water heater, no hot water

1. Check the error code on the display panel. Most tankless units show a fault code when something goes wrong. Write down the code.
2. Check the gas supply (gas units) or breaker (electric units).
3. Check for flow issues, tankless heaters need a minimum flow rate to activate. If only one faucet isn’t getting hot water, the flow may be too low to trigger ignition.
4. Call us with the error code, we service all major tankless brands (Navien, Rinnai, Rheem) and can usually diagnose the issue over the phone.

Strange Noises

Rumbling, popping, or banging from the tank

What it means: Sediment has built up at the bottom of the tank. When the burner fires, it heats the water trapped under the sediment layer, creating steam bubbles that pop and rumble. This is the most common noise complaint.

Is it dangerous? Not immediately, but it means your water heater is working harder than it should. Sediment reduces efficiency, increases energy costs, and accelerates tank corrosion.

What to do: Schedule a maintenance flush. We drain the tank, flush the sediment, inspect the anode rod, and check the overall condition. This can add years to your water heater’s life. Call (603) 440-8113 to schedule.

Screeching or whistling

What it means: A valve isn’t fully open (usually the inlet valve or T&P valve), causing water to force through a narrow opening.

What to do: Check that the cold water supply valve above the tank is fully open (turned all the way counterclockwise). If the noise persists, call us.

Ticking or tapping

What it means: Usually thermal expansion, pipes expanding and contracting as hot water flows through them. This is normal and not a concern in most cases.

You Smell Gas Near the Water Heater

This is the most serious situation on this page.

1. Do NOT touch any switches, buttons, or controls on the water heater or nearby.
2. Do NOT use your phone in the immediate area.
3. Leave the house immediately with everyone, including pets.
4. From outside, call 911, then your gas utility (Liberty Utilities for most of southern NH).
5. Do NOT return inside until cleared by the fire department or gas utility.
6. After the all-clear, call us at (603) 440-8113, we’re licensed for gas line work and can repair or replace the water heater safely.

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When to Repair vs. Replace

Use this quick decision guide:

Situation	Recommendation
Water heater is under 8 years old, repair cost is under $500	Repair
Water heater is 8-12 years old, one-time repair	Repair (but start planning for replacement)
Water heater is over 12 years old	Replace (even if still working, failure is imminent)
Tank is leaking from the bottom	Replace (not repairable)
Multiple repairs in the past 2 years	Replace (throwing good money after bad)
Energy bills have been climbing	Replace with a more efficient model

Keep This Number Handy

American Water Heater Pros: (603) 440-8113

Licensed Master Plumber #3613, serving Merrimack, Nashua, Hollis, Amherst, Bedford, Litchfield, Hudson, Londonderry, Milford, and all of southern NH.

We offer same-day water heater service for emergencies. Call anytime.