Nobody plans for a cold shower or a puddle next to the water heater. Yet an aging unit can cause both, often with little warning. So how long do water heaters last, and how can you tell when yours is close to the end?
In this guide, ARS®/Rescue Rooter® gives you a straight answer on water heater lifespan. You'll learn what wears a unit down, how to check its age, and how to decide whether to repair or replace it.
Already dealing with a leak or no hot water? Our team handles water heater services seven days a week, with upfront written estimates before work begins. Call your local ARS branch to get help.
How Long Do Water Heaters Last?
As a general recommendation, plan on replacing a water heater every seven to eight years. The actual lifespan varies with usage, climate, maintenance history, and installation quality.
So how long does a hot water heater last in your home? Here, "lifespan" means the point where repair costs and leak risk start to outweigh what the unit is worth. Your water heater may keep making hot water past that point, but the odds of a sudden failure tend to rise.
Tank vs. Tankless: How the Type Affects Lifespan
A tank water heater stores water and keeps it hot around the clock. Inside the tank is an anode rod, a metal rod that corrodes so the steel tank doesn't. Once that rod wears down, the tank itself can start to rust.
A tankless unit heats water only when you turn on a tap, so it avoids tank corrosion. Its weak point is the heat exchanger, the part that passes heat from the burner or element into the water. The Building America tankless scaling guide notes that in hard water areas, "scale can build up on the piping in the heat exchangers."
The same guide adds, "This reduces capacity and efficiency and in extreme situations can cause complete water heater failure." Here's how the two types compare.
| Factor | Tank Water Heater | Tankless Water Heater |
|---|---|---|
| How it works | Stores and heats a full tank of water | Heats water on demand as it flows through |
| Main wear point | Anode rod and tank corrosion | Scale buildup in the heat exchanger |
| Key maintenance | Yearly flush and anode rod checks | Descaling on the manufacturer's schedule |
| Longevity | Plan on replacing every seven to eight years | No tank to corrode; regular descaling may help it last |
| Typical install cost (ARS data) | About $2,300 to $3,500 | About $4,400 to $6,500 |
If you're weighing a switch to on-demand hot water, learn more about our tankless water heater services.
How to Tell How Old Your Water Heater Is
You can't judge a water heater's age by how it looks. The good news? You can usually find the answer in a few minutes.
- Find the rating plate: The rating plate is the manufacturer's label on the unit. It lists the model number, serial number, and capacity.
- Read the serial number: The serial number usually encodes the build month and year. The format varies by brand, so check the manufacturer's decoding guide.
- Confirm the install date: The build date isn't the install date, since units can sit in storage first. Check your closing documents or install receipts.
- Ask for help if needed: If you can't decode the serial number, an ARS technician can help during a service visit.
What Shortens a Water Heater's Life
Several everyday factors can wear a water heater down faster than normal. Many of them are things you can check at home.
- Hard water and sediment: Sediment is the sand-like mineral layer at the bottom of a tank. It can make the unit work harder and may cause rumbling.
- High temperature settings: Hotter water can speed up mineral buildup and corrosion. Check the dial on your thermostat or gas valve. 120 F is the recommended water heater setting for most households.
- High water pressure: Pressure spikes can strain the tank and valves. Local codes may require a pressure-reducing valve or expansion tank, so check what's installed.
- Heavy use or an undersized tank: A tank that's too small for your household may run almost nonstop. Notice how often hot water runs out.
- Worn-out anode rod: Once the rod is used up, corrosion can attack the tank itself. Find out when it was last inspected.
- Skipped maintenance: Without regular flushing, sediment can build up year after year. Look for a service tag or past invoices.
- Poor installation: Incorrect sizing, venting, or connections can shorten a unit's life. Watch for scorch marks, leaky fittings, or odd smells.
Thermal expansion is worth a closer look. In a closed plumbing system, the Rheem thermal expansion bulletin says repeated pressure can "stress" the tank, weakening welds and fittings. A closed system is one where a check valve or backflow preventer keeps heated, expanding water from flowing back toward the main.
Hard water deserves extra attention, too. When it's heated, the U.S. Geological Survey explains, calcium carbonate deposits called scale can form inside the water heater.
According to USGS water hardness explained, this scale "can reduce the life of equipment" and "lower the efficiency of electric water heaters." It can also raise heating costs and clog pipes. To see what minerals do to the rest of your home, read about how hard water affects plumbing.
Signs Your Water Heater Is Near the End
Water heaters often give some warning before they fail. Use this checklist to see whether yours is showing its age. For a closer look at each symptom, review these signs you need a new water heater.
- Rumbling or popping noises: The Rheem water heater maintenance guide says these sounds "usually indicate sediment accumulation at the bottom of the tank."
- Rusty or discolored hot water: Rheem notes that rust-tinted or cloudy water "points to corrosion or high mineral content inside the tank or pipes."
- Water pooling at the base: Even a small puddle can mean the tank or a fitting is leaking.
- Slower reheating or less hot water: Rheem notes that sediment or scale may be "restricting heat transfer or water flow."
- Uneven temperatures: Rheem notes sudden hot and cold shifts can signal mineral buildup in the heat exchanger, a faulty thermostat, or flow sensor issues.
- Age at or past the recommended mark: A unit that's seven to eight years old deserves a closer look, even without other symptoms.
If you find a leak, take these steps first to help limit water damage:
- Shut off the cold water supply: Turn the valve on the cold water line above the unit clockwise until it stops.
- Turn off the power or gas: Switch off the breaker for an electric unit. Turn the gas knob to "Off" or "Pilot" for a gas unit.
- Stay clear of wet electrical areas: If water has reached outlets or your electrical panel, don't touch them. Wait for help.
- Protect your belongings: Move boxes and valuables away, and use towels to contain the water.
Once the water is under control, call your local ARS branch. Our trained plumbing team handles leaking and failed water heaters seven days a week.
Should You Repair or Replace Your Water Heater?
Two things usually decide it: your unit's age and the cost of the repair. A small fix on a younger unit is often worth it. A big repair on an older unit rarely is.
The sections below give you a clear way to weigh both. Our guide on whether to repair or replace your water heater walks through even more scenarios.
When a Repair Makes Sense
Repair usually makes sense when your water heater is younger, one part has failed, and the tank isn't leaking. Parts that can fail on their own include the thermostat, heating element, igniter, and valves.
One caveat: a leak from the tank body itself generally can't be repaired. Once the tank wall corrodes through, water heater replacement is the safe option.
When Replacement Is the Smarter Move
ARS recommends a general rule for homeowners that starts with your repair quote. Is the quote more than half the cost of a new system? If so, and the unit is over 10 years old, replacement usually makes more financial sense over the life of the system.
Replacement also tends to be the better choice if the tank leaks, repairs keep piling up, or your energy bills keep climbing. Per DOE water heating costs, "the average household spends 14%-18% of their utility bill on water heating - that equates to approximately $400-$600 each year." A newer, more efficient unit may help lower that share.
| Situation | Recommendation |
|---|---|
| Younger unit, one failed part, no leak | Repair is usually worth it |
| Leak from the tank body | Plan on water heater replacement |
| Repair quote over half the cost of a new unit, and unit over 10 years old | Replacement usually makes more financial sense |
| Repeat repairs in a short span | Get a replacement estimate |
| Unit at or past seven to eight years with warning signs | Start planning a replacement |
| Rising energy bills and slower hot water recovery | Schedule an inspection to weigh your options |
What Water Heater Replacement Typically Costs
According to ARS, a standard tank water heater replacement typically ranges from about $2,300 to $3,500, depending on capacity and installation requirements. ARS reports that tankless water heater installations typically run between about $4,400 and $6,500, depending on unit type and installation complexity.
These ranges come from ARS national service data covering January 2025 through January 2026. They aren't fixed prices, and your cost may vary with your home's setup and the unit you choose.
Before any work begins, ARS provides an upfront written estimate. If you'd like to spread out the cost, ask about our flexible financing options.
How to Help Your Water Heater Last Longer
Regular care may help extend your water heater's life and keep it running efficiently. Some steps are easy to handle yourself. Others involve scalding water, gas, or high pressure, so they're best left to a professional.
- Flush sediment yearly: Draining the tank about once a year may help clear sediment. Flush more often if you have hard water.
- Inspect the anode rod: Have it checked at least once a year, as manufacturers recommend. Replace it when it's worn.
- Set the temperature around 120°F: This setting may help slow wear and lower the risk of scalds.
- Test the T&P valve periodically: The temperature-and-pressure relief valve, or T&P valve, releases excess pressure. Testing is best left to a professional.
- Check pressure control: Confirm your home has the pressure-reducing valve or expansion tank your local code requires.
- Descale tankless units: Follow the manufacturer's descaling schedule to help keep scale out of the heat exchanger.
Manufacturer guidance backs up these steps. Per A. O. Smith flushing guidance, most tank models need a flush at least yearly, and hard water areas may need more. For tankless units, A. O. Smith says to follow your manufacturer's handbook for descaling.
A. O. Smith also explains that the anode rod is "sacrificed" to protect the tank from corrosion, and it recommends inspecting the rod once a year. A DOE-commissioned water heater study suggests a first check after three to four years for normal water, though it notes many manufacturers recommend yearly checks.
The study says to replace the rod when more than six inches of bare core wire is visible. It also calls for replacement if the rod has corroded to under half its original diameter, or shows heavy pitting or splitting.
For the T&P test, Rheem describes lifting the valve's handle briefly so water flows freely through the discharge pipe. If the valve doesn't release properly or keeps leaking afterward, Rheem says to replace it.
The temperature tip has solid backing, too. Most households need only 120ºF, and the DOE water heater temperature guidance says it "slows mineral buildup and corrosion in your water heater and pipes." The CPSC tap water scald guidance also "urges all users to lower their water heaters to 120 degrees Fahrenheit."
To fine-tune your dial, see our guide to the best water heater temperature setting. You can also browse more water heater maintenance tips to use between service visits.
How Often Should You Service Your Water Heater?
A yearly professional checkup and flush is a sensible baseline for most homes. If you have hard water, plan on service more often. Regular visits may help catch a worn anode rod, a sticky T&P valve, or a small leak before it becomes a bigger repair.
Want help staying on schedule? The Pro Service Plan includes two HVAC preventive maintenance visits per year. Plumbing maintenance, including a whole-home plumbing inspection and water heater flush, is available as an optional add-on.
When to Call a Professional
Some water heater problems shouldn't wait. Call for help if you notice any of these:
- Active leaks or pooling water: Shut off the water and the power or gas first, then call.
- Rust in your hot water: Discolored water can point to a corroding tank.
- No hot water: A failed heating element, igniter, or thermostat may be to blame.
- A gas smell: Leave your home right away and call your gas utility from outside.
- A discharging T&P valve: Water coming from this safety valve can signal too much heat or pressure.
- An aging unit with symptoms: A unit past seven to eight years with any warning sign is worth a replacement estimate.
Our trained, experienced plumbing team is available seven days a week. You'll get an upfront written estimate before work begins, and our work is backed by the Exceptional Service Guarantee.
**Call your local ARS/Rescue Rooter branch or **Schedule Service Online.
Frequently Asked Questions
ARS's general recommendation is to plan for replacement every seven to eight years, though actual life varies with usage, water quality, maintenance, and installation. Any extra years are worth watching closely for warning signs.
Usually not, if the repair costs more than half the price of a new unit. In that case, ARS's general rule says replacement usually makes more financial sense over the life of the system.
Your unit is well past the general seven-to-eight-year recommendation. Planning a water heater replacement before it leaks may help you avoid water damage and a rushed emergency install.
Yes, it can. According to the USGS, scale from heated hard water can reduce the life of equipment and lower the efficiency of electric water heaters.
Check it at least once a year, as A. O. Smith recommends, and replace it when it's heavily worn. Softened water can wear the rod faster, so mention any water softener during service.
Not necessarily: the Rheem limited warranty terms cover defects in materials and workmanship under normal use for a set period, not a service life. They also exclude failures caused by improper installation or a lack of maintenance.
Tankless units don't store water, so they avoid the tank corrosion that wears out storage models. Their weak point is scale in the heat exchanger, and regular descaling may help them last.
