No Hot Water? Why Your Water Heater Stopped Working

You turn on the shower, wait, and the water never warms up. Or it starts warm and goes ice cold halfway through. No hot water is one of the most common calls a plumber gets, and the good news is that the cause is usually a single worn part rather than a dead water heater.

This guide describes possible causes of lost hot water and information to prepare for a professional assessment. It is not a diagnosis or a procedure for working on gas or electrical equipment. The site publishes information and collects enquiries; the guide does not book professional attendance.

Start here: is it the whole house or one faucet?

Before you head to the basement, run hot water at two or three fixtures, ideally on different floors. The answer changes where you look.

• No hot water anywhere: the problem is at the water heater itself. Keep reading.
• One faucet or shower runs cold, others are fine: the heater is working. The likely culprit is that fixture's mixing valve or cartridge, which can stick or fail and block hot water from reaching the spout.
• Hot water comes, but runs out fast: the heater is producing heat, just not enough of it. Skip to the section on hot water running out.

This two-minute check saves a lot of guesswork, and it is the first thing a plumber will ask you on the phone.

Gas water heater with no hot water

Many Omaha homes heat water with natural gas supplied by MUD, so start here if you have a flue pipe coming off the top of your tank.

The pilot light is out

On older, standing-pilot heaters, a small flame burns continuously to light the main burner. Look through the small sight window near the bottom of the tank. No blue flame means the pilot is out.

A pilot can go out for different reasons. The appropriate checks depend on the exact equipment and its condition. This guide does not provide a generic relighting sequence; refer to the manufacturer instructions and seek qualified help if uncertain.

The pilot lights, but won't stay lit

This is the classic sign of a failing thermocouple. The thermocouple is a thin copper rod that sits in the pilot flame. As long as it senses heat, it tells the gas valve it is safe to keep gas flowing. When it wears out, it stops sending that signal, and the valve shuts the pilot off as soon as you let go of the knob.

The cause needs assessment rather than assuming that replacing one component will resolve it. Work on gas components belongs with a qualified professional familiar with the equipment.

Newer heaters: igniter, flame sensor or flame arrestor

Many gas heaters built in the last decade use an electronic igniter instead of a standing pilot, and some have a status light that blinks an error code. The code chart is usually on the label or inside the access cover. Common failures are a weak igniter or a dirty flame sensor.

There is one detail most homeowners never hear about. Gas water heaters made since the early 2000s have a flame arrestor screen at the base to prevent them from igniting flammable vapors. If that screen gets clogged with lint, dust or pet hair, the burner starves for air and the heater locks itself out. This is common when a water heater sits next to a dryer or in a dusty unfinished basement. It is a safety component, so cleaning it is a job for a pro.

The gas control valve has failed

If the pilot stays lit but the main burner never fires, or the control knob will not turn, the gas control valve (the box on the front of the tank with the temperature dial) may have failed. This is one of the pricier repairs. On an older tank, it is often the point where replacing the heater makes more sense.

If you smell gas: leave the building without using switches or phones inside. From a safe place, call M.U.D. at 402-554-7777 or 911. See M.U.D. natural gas safety guidance. Do not send a gas emergency to this site.

Electric water heater not heating

Electric water heaters are simpler, and most no-hot-water problems come down to power, the reset button, or a heating element.

Check the breaker

An electrical supply problem can be one cause of lost hot water. Describe any visible indication to the professional assessing the unit. This page does not instruct you to reset breakers or investigate wiring.

Check the high-limit reset button

The high-limit control is a safety component. Its condition and the cause of a trip need assessment; this guide does not instruct you to remove access covers or reset it.

A repeated trip can indicate an unresolved fault. Ask a qualified professional to diagnose the cause rather than treating a reset as a repair.

A heating element has burned out

Most residential electric heaters have two elements, one upper and one lower. The pattern of the failure tells you which one:

• No hot water at all: often the upper element or upper thermostat, since the upper element has to heat before power passes to the lower one.
• A little lukewarm water that runs out fast: usually the lower element, which does most of the work.

Omaha's hard water plays a big role here. Minerals settle to the bottom of the tank and bury the lower element in sediment. The element runs hotter than it was designed to, and eventually it burns out. Our guide to a water heater making a rumbling noise explains how sediment builds up and how to deal with it.

Testing or replacing electrical components requires equipment-specific procedures and qualified assessment. No procedure for opening or working inside the unit is provided here.

Hot water runs out too fast

If you get some hot water, just not enough, look at these causes:

• Sediment buildup. Every inch of mineral buildup at the bottom of the tank takes the place of water and insulates the burner or element from the water it is supposed to heat. Tanks in homes without a water softener are hit hardest. Here is more on how Omaha's hard water affects your plumbing.
• A broken dip tube. The dip tube carries incoming cold water to the bottom of the tank. If it cracks or breaks off, cold water mixes in at the top, right where hot water leaves. A telltale sign is small white plastic flakes clogging faucet aerators.
• The thermostat is set too low. About 120°F is the usual recommendation for safety and efficiency. If someone turned it down, or the dial got bumped, you will notice short showers first.
• The heater is too small for the household. A 40-gallon tank that worked for two people may not keep up with a family of five.
• Winter. Incoming water in Omaha gets much colder from December through February. The heater has to raise the temperature a lot more, so recovery slows and the same tank delivers noticeably less. A marginal unit often shows its age in the first real cold snap.

What about tankless water heaters?

Tankless units usually display an error code when something is wrong, and the code is the fastest route to the cause. The most common issues are mineral scale inside the heat exchanger, a clogged inlet filter, and flow too low to trigger the burner, which is why a single trickle at the sink may not produce hot water. With hard water, most manufacturers recommend descaling at least once a year. Power-vented and tankless gas units also need electricity to run, so a power outage means no hot water even though the gas is on.

Factors that affect a repair quote

The failed component is only part of the scope. Equipment type, access, diagnostic work, parts availability and the condition of the tank can affect the options and charges. A gas control valve repair can involve a different scope from another component; no unverified amount is supplied here.

Ask the professional assessing the unit to explain what the diagnosis establishes, what a repair would include and whether replacement is an alternative. This site does not issue plumbing quotes or provide a verified current local repair tariff.

When to call a plumber

Seek qualified assessment rather than treating the descriptions above as permission to work on the unit. Describe symptoms such as:

• The pilot will not stay lit, or the burner will not fire after a relight.
• The breaker or reset button trips more than once.
• You see water pooling around the base of the tank along with the heating problem.
• You smell gas or see scorch marks around the burner access. Call MUD first for a gas smell.
• The heater is more than 10 years old and you want an honest repair-or-replace answer.

The water heater information page explains questions to prepare for assessment, with related area information for Dundee and West Omaha and Millard. The emergency plumbing information explains the limits of this site. These information pages do not confirm a contractor’s availability, after-hours attendance or a booking.

Next steps

Record whether the problem affects every fixture, the unit type and any visible error message without opening the equipment. A professional needs to assess the actual fault and explain the repair or replacement options. This site does not diagnose the problem, arrange a visit or provide a quote.

Use the contact page only for non-urgent enquiries about the site or content corrections. Submitting a message does not book a plumber or guarantee a response.