Most people do not give their water heater a second thought until they are standing in a cold shower or see a plumber’s truck in their driveway. But there is another situation that tends to sneak up on homeowners: the electric bill that keeps climbing with no obvious explanation. You have not changed your habits, nothing new got plugged in, and yet the bill is noticeably higher than it was six or twelve months ago.
If that sounds familiar, your water heater deserves a hard look. So can a bad water heater raise electric bill? Yes, it absolutely can, and in some cases it is responsible for a surprisingly large chunk of the extra cost. Water heating already accounts for roughly 14 to 18 percent of a typical household’s total energy use, so when something goes wrong with the unit, the impact on your bill is not subtle. This guide covers exactly what causes a water heater to start consuming more electricity than it should, how to diagnose the problem, and what it costs to fix it.
A failing or poorly maintained electric water heater can definitely drive up your electricity costs. The most common reasons include sediment buildup forcing the elements to run longer, one or both heating elements beginning to fail, a faulty thermostat holding the unit at the wrong temperature, deteriorating tank insulation causing excessive heat loss, or the unit simply being too old to operate efficiently. Any of these issues makes the water heating system work harder than it needs to, and that extra effort shows up on your monthly bill.
Why a water heater starts using more electricity over time
A water heater does not fail all at once in most cases. It degrades gradually, and one of the earliest signs of that degradation is a quiet but steady increase in energy consumption. Here is what is actually happening inside the unit when costs start creeping up.
Sediment buildup on the heating elements
In areas with hard water, calcium and magnesium deposits build up inside the tank over time. On electric water heaters, this sediment coats the lower heating element directly, acting as an insulating layer between the element and the water it is supposed to heat. The element has to stay on longer and run hotter to push heat through that layer and bring the tank up to temperature. Over several years of buildup, this can add a meaningful amount to your energy use without you ever knowing why. Homeowners in hard water areas often see this problem develop faster, sometimes within two or three years of installation.
The rumbling or popping sounds that come from a tank during heating cycles are often the sound of water boiling underneath sediment deposits. If you have been hearing that noise and also noticing higher bills, the connection is real.
A failing heating element
Most tank-style electric water heaters have two heating elements: one near the top of the tank and one near the bottom. When the lower element begins to fail, the upper element picks up the slack and runs far more than it was designed to. The water heater may still produce hot water, just more slowly and at greater energy cost. A partially failed element can draw more current than a healthy one because it is struggling, similar to how a car with a bad cylinder still runs but burns more fuel doing it.
A failed or failing element is one of the most common repairs on electric tank water heaters and one of the most cost-effective fixes if caught before it causes other damage.
A faulty thermostat
Electric water heaters use thermostats to control when the heating elements turn on and off. When a thermostat starts failing, it can lose accuracy and allow the tank to heat beyond the set temperature, essentially running the elements longer than needed. A thermostat stuck in the “on” position is particularly wasteful because the element runs continuously regardless of whether the water actually needs more heat. You may not notice the water is hotter than usual right away, especially if you use a mixing valve at the tap, but the bill will reflect it.
Deteriorating tank insulation
The foam insulation surrounding your water heater’s tank keeps heat inside the unit so it does not have to reheat as frequently. Over time, especially on older units, this insulation compresses, degrades, or develops gaps. The tank loses heat to the surrounding environment faster, which triggers the thermostat to run the elements more often to maintain temperature. In an uninsulated garage or basement where temperatures drop significantly in winter, this effect is amplified.
Some homeowners add an external insulation blanket to an older tank to reduce standby heat loss. These blankets cost $20 to $40 and can modestly reduce energy consumption, though they are more of a temporary measure than a long-term solution for a genuinely aging unit.
The unit is simply too old
Electric water heaters have an average lifespan of about 10 to 12 years. As they age, efficiency declines across the board. Elements scale up, thermostats drift, anode rods deplete, and the cumulative effect is a unit that uses noticeably more electricity to deliver the same amount of hot water it managed easily when it was new. If your water heater is approaching or past the 10-year mark and your bills have been trending upward, age is a legitimate explanation. Repairing an old unit can buy time, but at some point the economics favor replacement.
How to tell if your water heater is the cause
The most practical first step is to look at your energy bills over the past 12 to 24 months and identify when the increase started. If it coincides with a change in season, that could be weather-related rather than a faulty appliance. If the increase is consistent across seasons and does not match any change in usage patterns or new appliances, the water heater is worth investigating.
You can also do a basic test by turning off the water heater at the circuit breaker for 24 to 48 hours while maintaining otherwise normal household behavior. If your daily electricity usage drops noticeably during that period, the water heater was consuming a disproportionate amount. This is not a long-term solution obviously, but it helps confirm whether the appliance is the source of the problem before spending money on a service call.
Another indicator is recovery time. A healthy electric water heater recovers a full tank of hot water within 60 to 90 minutes depending on tank size. If you are running out of hot water faster than you used to, or it takes longer to recover, the heating elements are likely struggling and working overtime in the process.
How to fix it
Flush the tank to remove sediment. This is a free maintenance step and the first one to try. Connect a garden hose to the drain valve at the bottom of the unit, shut off the cold water supply and power to the unit at the breaker, then let the tank drain fully. For tanks with heavy sediment, briefly restoring cold water a couple of times while draining can help flush deposits out. This process takes about an hour and can meaningfully improve element efficiency. Having a plumber do it typically costs $80 to $200.
Replace the heating elements. If one or both elements are failing, replacing them is a manageable repair. The parts themselves cost $15 to $40 each depending on the wattage and type. A plumber will typically charge $150 to $300 for the job including labor, though this varies by region. Replacing elements before they fail completely is usually cheaper than waiting for a full breakdown.
Replace the thermostat. A faulty thermostat on an electric unit costs $20 to $50 for the part. With labor, total repair cost usually falls between $100 and $200. It is worth replacing both the thermostat and the element at the same time if both are showing signs of age, since the labor cost is largely the same either way.
Add tank insulation. Wrapping an older tank in an insulation blanket is a quick and inexpensive step that can reduce standby heat loss, particularly in cold environments. Make sure the blanket is compatible with your unit’s specifications, as some manufacturers do not recommend them if the unit already has adequate built-in insulation. Your unit’s label or manual will indicate this.
Consider upgrading to a heat pump water heater. If your electric water heater is more than eight years old and showing efficiency problems, this is worth seriously considering. Heat pump water heaters use electricity to move heat from the surrounding air into the tank rather than generating heat directly, making them two to three times more efficient than a standard electric resistance unit. They cost more upfront, usually $800 to $1,500 for the unit, with installation adding $300 to $600, but the ongoing energy savings can cut your water heating costs by 50 to 70 percent annually. In many states and countries, rebates or tax credits are available that reduce the upfront cost significantly.
When to call a professional
If your electric bill is significantly elevated and the basic checks above do not point to an obvious cause, a licensed electrician or plumber can perform a more thorough diagnosis. They can test the elements for resistance, check thermostat accuracy with a calibrated gauge, inspect the wiring for faults, and assess the overall condition of the unit. This kind of service call typically costs $75 to $150 for the inspection alone.
You should also call a professional if you notice any of the following alongside rising bills: water that is noticeably hotter than usual at the taps, a burning smell near the water heater, any signs of moisture or leaking around the unit, or a circuit breaker that keeps tripping. A breaker that repeatedly trips on a water heater circuit suggests an electrical fault that needs attention quickly, not just for efficiency reasons but for safety.
What repairs and replacement typically cost
Replacing a heating element runs $150 to $300 installed. A thermostat replacement costs $100 to $200. A full flush and service visit costs $80 to $200. If the unit needs a new anode rod, which helps prevent internal corrosion and affects long-term efficiency, that is typically $50 to $100 for the part plus $100 to $150 in labor.
If the verdict is full replacement, a standard electric tank water heater runs $400 to $900 for the unit depending on size and brand tier, with installation typically adding $200 to $500. A heat pump water heater runs higher at $800 to $1,500 for the unit, plus $300 to $600 installed, but long-term operating costs are substantially lower. Prices vary in other markets, with the UK, Canada, and Australia seeing broadly comparable figures adjusted for local labor rates.
Common mistakes homeowners make
The most common mistake is attributing rising electricity costs to everything except the water heater. People look at their lighting, their HVAC, their standby electronics, and rarely think to check the water heater until the bill has been high for a year or more. Given that water heating is one of the largest single energy draws in most homes, it should be near the top of the list when investigating unexplained bill increases, not near the bottom.
Another mistake is doing a partial repair when a full one is warranted. Replacing one failed element while leaving a five-year-old thermostat in place, or flushing the tank without also checking the elements, often means the problem comes back within a year. If the unit is going to be serviced, it makes sense to address all the likely contributors at once. That is usually where things go wrong with a piecemeal approach.
Prevention tips
Flush your water heater once a year to keep sediment from building up. Set the thermostat to 120 degrees Fahrenheit, which is warm enough for all household needs while avoiding unnecessary energy use. In a cold garage or basement, consider adding an insulation blanket to the tank. Have the anode rod checked every three to five years and replaced when depleted. And if your unit is approaching the 10-year mark, start comparing replacement options now rather than waiting for a breakdown, because the efficiency of an aging unit will only continue to decline.
Read more: Can a bad water heater cause low water pressure
It’s only normal to ask questions like can a bad water heater raise electric bill. A water heater that is struggling quietly can cost you hundreds of dollars a year in excess electricity before it ever stops producing hot water. The fix is often simpler and cheaper than people expect, and in many cases a single service visit solves the problem entirely. But if the unit is old and showing multiple signs of decline, replacement is genuinely worth running the numbers on. The energy savings from a new, efficient model can pay back the investment faster than most homeowners assume, especially if you move to a heat pump option with available rebates.
