Water & Pipe Emergency
No Hot Water? Here's How to Figure Out Why.
Whether you have a gas or electric water heater, there are a few common reasons hot water stops suddenly. Some you can fix yourself in minutes. Others need a pro.
What's Going On
Understanding the Problem
When a water heater stops producing hot water, it's almost always one of a handful of issues: the pilot light is out (gas), a heating element has failed (electric), the thermostat has tripped or failed, sediment has built up to the point of insulating the water from the heat source, or the unit has simply reached the end of its service life. Houston's hard water is particularly hard on water heaters — mineral scale builds up inside the tank and on heating elements faster here than in most other Texas cities.
Diagnosis
Common Causes
1Pilot light outage (gas water heaters)
The most common reason for sudden hot water loss in gas water heaters is a pilot light that has gone out. This can happen from a gust of air, a brief interruption in gas supply, or simply because the thermocouple (the sensor that keeps the pilot on) has worn out. If the thermocouple is faulty, the pilot will relight but immediately go out again — this means the thermocouple needs replacement, which is a straightforward repair.
2Tripped high-temperature limit switch (electric water heaters)
Electric water heaters have a safety switch — sometimes called the 'reset button' — that trips when the water temperature gets too high. It's a red button located behind an access panel on the side of the tank. This sometimes trips randomly due to a power surge, but if it trips repeatedly, it usually indicates a failing thermostat or heating element that is causing the water to overheat.
3Failed heating element (electric water heaters)
Most electric water heaters have two heating elements — one upper and one lower. The lower element handles most of the ongoing heating load and fails more frequently. A failed lower element means you still get some hot water (from the upper element) but run out much faster than usual. A failed upper element means very little hot water at all. Elements are relatively inexpensive but the repair does require working around 240-volt power.
4Sediment buildup inside the tank
Houston's water supply carries a significant amount of dissolved calcium and magnesium. Over time — typically within 3–5 years without maintenance — these minerals settle at the bottom of the tank as sediment. The sediment layer insulates the water from the burner or lower heating element, dramatically reducing efficiency and heating capacity. You'll notice the water takes longer to recover and isn't as hot as it used to be. You may also hear popping or rumbling sounds from the tank as water boils under the sediment layer.
5Thermostat set too low or failed
Water heater thermostats can drift or fail over time. If the thermostat is set below 120°F, you may not perceive the water as adequately hot, especially in winter when cold water entering the tank is colder than usual. If the thermostat has failed, it may stop signaling the heating elements or burner to fire at all.
6Water heater at end of service life
The average tank water heater lasts 8–12 years. In Houston, with hard water and high usage, the realistic lifespan is often on the lower end of that range. An aging unit may stop heating effectively before it fails outright — you may have lukewarm water rather than no hot water. If your unit is over 10 years old and losing capacity, repair costs should be weighed against the cost of replacement.
DIY Troubleshooting
What You Can Try
Relight the pilot light on a gas water heater
Turn the gas control knob to 'Pilot.' Press and hold the pilot button (or the control knob on older units) to allow gas to flow to the pilot, then use a long lighter to ignite it. Hold the button for 30–60 seconds after the pilot lights to allow the thermocouple to heat up. Release slowly — if the pilot stays lit, turn the knob to your desired temperature setting. If the pilot won't stay lit after releasing, the thermocouple likely needs replacement.
Press the reset button on an electric water heater
Locate the access panel on the upper portion of the tank (most electric heaters have two panels; start with the upper one). Behind it, you should see a red button — press it until you feel or hear a click. Replace the cover, wait 30–60 minutes, and test hot water. If the button trips again within a day, there is an underlying electrical problem that needs professional attention.
Check the circuit breaker for an electric water heater
Electric water heaters run on a dedicated 240-volt double-pole breaker. Find it in your electrical panel — it should be labeled 'Water Heater.' If the breaker is tripped (switched to the middle position), reset it by pushing it fully to the off position first, then back to on. If it trips again immediately, there is an electrical fault and you should leave the breaker off and call a plumber or electrician.
Flush sediment from the tank (if you're comfortable doing so)
Connect a garden hose to the drain valve at the base of the tank, run the hose to a floor drain or outside, shut off the cold water supply to the heater, turn the heater to 'Pilot' or off, then open the drain valve. Let water flow until it runs clear. Close the valve, remove the hose, turn the cold water supply back on, let the tank refill fully, then relight or reset. Annual flushing prevents most sediment-related issues.
Check whether the problem is isolated to one fixture
If hot water is absent from one faucet but present elsewhere in the house, the problem may be a failed cartridge or mixing valve at that specific fixture rather than the water heater itself. Test two or three different faucets before assuming the heater is at fault.
Know When to Call
When to Call a Pro
Call ARG Plumbing at (832) 419-3411 if the pilot won't stay lit after relighting, if the reset button trips more than once, if you smell gas near the water heater at any time, or if your unit is over 10 years old and showing signs of decline. Water heater repair and replacement is one of our most common calls — we carry tank and tankless units and can often replace a failed heater promptly.
Pro Tip
Set your water heater thermostat to 120°F — not higher. Many water heaters come from the factory set at 140°F. At 140°F, you waste energy heating water hotter than you need, and you accelerate mineral scale buildup at the bottom of the tank because higher temperatures cause calcium to precipitate out of solution faster. 120°F is hot enough to kill Legionella bacteria, safe enough to prevent scalding, and gentler on the tank.
Hristo
Master Plumber · ARG Plumbing