Short answer
The US Department of Energy says storage tank water heaters last 10 to 15 years, and most tankless heaters have a life expectancy of more than 20 years. ENERGY STAR says that if you suspect your heater is over 10 years old, it is time to consider replacing it before it fails. Water quality and maintenance change the outcome.
Water heater lifespan is a range, not a date, and water heater age is only one part of it. This page covers the typical range from the US Department of Energy and what ENERGY STAR advises, how to find your heater's age from its label, the signs a water heater is failing, the maintenance that helps, how to think about repair versus replacement without guessing at prices, and where permits come in.
How long does a water heater last
Here is what the sources say about water heater lifespan.
| Source | What it says |
|---|---|
| US Department of Energy (Energy Saver) | Storage water heaters last 10 to 15 years. Most tankless water heaters have a life expectancy of more than 20 years, with easily replaceable parts that may extend their life by many more years. |
| ENERGY STAR | If you suspect your water heater is more than 10 years old, it is time to consider replacing it, rather than waiting for an emergency. Its heat pump water heater savings table assumes a 13-year lifespan for that type. |
| Natural Resources Canada | Water quality is the single most important factor affecting the life of the water heater. It also says a warranty is not always a good measure of reliability. |
So 10 years is the planning point and 15 is the upper end of what to expect from a storage tank, not a promise. Natural Resources Canada says water quality is the biggest factor, and the Department of Energy says maintenance can extend life, so a tank in hard water or one never maintained may fall short of the range. The Department of Energy says tankless heaters typically last longer.
Water heater age: how to read the label
You may not know when your heater was made. ENERGY STAR's guidance is to find the brand name and serial number on the tank label. In some cases the date of manufacture is printed on the same label. If it is not, the serial number can be decoded using manufacturer or industry resources. ENERGY STAR's page points to online references from several manufacturers and inspection bodies.
- Manufacturers differ. ENERGY STAR points to separate decoding resources from several manufacturers, which suggests there is no single serial number format. Do not guess from the number alone.
- Check the label for the date or ask the maker. Take a clear photo of the rating label, with model and serial number, and ask the manufacturer's customer service or use its published decoder.
- Manufacture date and install date can differ. A heater can sit in a warehouse before installation. Your installation invoice or home records may give the install date.
Write the age and model number in your home records.
Signs your water heater is failing
ENERGY STAR lists five warning signs of possible failure. A. O. Smith's consumer guide and the Consumer Product Safety Commission add context.
| Sign | What it may mean | What to do |
|---|---|---|
| Corrosion on or around the unit or its water lines | ENERGY STAR lists visible corrosion as a sign of possible failure | Have a plumber look at it |
| Leaks from joints, seals or seams | Same list. See water heater leaking: what to do | Shut off the water, call a plumber |
| Rust in the hot water | ENERGY STAR says it suggests internal corrosion | Call a plumber |
| Less hot water than before | ENERGY STAR links it to sediment buildup. For gas heaters the CPSC also lists a decreased hot water supply as a clue to improper appliance operation, so a check of the venting is sensible | See water heater not heating, then call a professional |
| Rumbling, popping or vibrating | ENERGY STAR and A. O. Smith link these to sediment on the tank bottom | Ask a plumber about flushing: how to flush a water heater |
| Relief valve discharging often | A. O. Smith says frequent opening may point to high pressure | Do not touch it. Call a plumber |
ENERGY STAR warns that ignoring signs can lead to sudden failure, cold water, a ruptured tank and water damage, and that an emergency replacement is often more expensive and can limit you to less efficient models. Know where your water shutoff is before you need it: how to shut off your water.
Maintenance that helps a water heater last
The Department of Energy says periodic maintenance can significantly extend a water heater's life and minimize loss of efficiency, and to read your owner's manual for specific recommendations. For storage heaters, depending on the model, it lists:
- flushing a quart of water from the tank every three months,
- checking the temperature and pressure valve every six months, and
- inspecting the anode rod every three to four years.
Other sources give different intervals. A. O. Smith advises draining a few gallons once a year, having a plumber check the anode rod once a year, and a licensed plumber inspection every couple of years. Natural Resources Canada explains that the anode rod dissolves at a rate that depends on the water's mineral content or hardness, and that water quality is the single most important factor in heater life. The sensible reading is that harder water calls for more attention, and your manual sets the schedule. See how to flush a water heater for safety and the cases where you should not try it.
The temperature setting also affects safety. The CPSC urges 120 degrees Fahrenheit for household heaters to reduce tap-water scalds. Do not change it casually, and ask a plumber to explain your options if anyone in the house is at risk of scalds or bacteria concerns.
When to replace a water heater: repair or replace
This guide does not quote repair or replacement prices, because none of the sources opened for it gives a reliable figure for your area. Get written quotes. Here are the decision factors to weigh.
- Age against the range. A heater under 10 years old with a failed part is a different conversation from one at 12 with a corroded tank. ENERGY STAR's 10-year line is the point to start planning.
- What failed. Ask the technician exactly which part and whether it is a replaceable component or the tank itself. Ask them to write it down. A. O. Smith, for example, says a faulty gas control valve should be inspected and replaced by a professional.
- Repeat repairs. If this is the second or third service call in a short time, that matters for the decision.
- Operating cost. The Department of Energy notes that the lowest-priced storage water heater may be the most expensive to operate and maintain over its lifetime. ENERGY STAR promotes certified heat pump models and says rebates may be available through the ENERGY STAR Rebate Finder or your utility. Programs change, so check current offers before you buy.
- Planned versus forced. Natural Resources Canada suggests replacing a heater close to the end of its life but before it fails, so you can make an informed choice instead of an emergency one.
- Size, fuel and venting. If you are changing type, see tankless vs tank water heaters and the water heater size calculator.
- Warranty. Natural Resources Canada notes a warranty is not always a good measure of reliability, so read what it covers, and check whether labour is included.
Replacement, installers and permits
The Department of Energy says proper installation depends on fuel type, climate, local building code requirements and safety issues, especially the combustion of gas and oil units, so it is best to have a qualified plumbing and heating contractor install your storage water heater. When selecting a contractor it advises requesting cost estimates in writing, asking for references, checking the company with your local Better Business Bureau, and asking whether the company will obtain a local permit if necessary and understands local codes. If you plan to install it yourself, consult the manufacturer first and contact your city or town about permits and local codes.
The CPSC adds that appliances should be installed according to the manufacturer's instructions and local codes, and that most should be installed by professionals. For ideas on how to compare companies, see drain cleaning near me: how to find and vet a company.
What to look up where you live
- Your local building department: permits for water heater work are set locally, so ask the local building department whether replacement needs one and who may pull it.
- Your state or provincial plumbing or contractor licensing board: to confirm the installer is licensed and check complaints.
- Your gas or electric utility: for rebates, and for gas safety inspection if you switch fuel type.
- Your water supplier: if water hardness is a concern, ask about local water quality.
For Canadian readers. Natural Resources Canada publishes a residential water heater guide and ENERGY STAR information for Canada, and provinces and municipalities set licensing and permit rules. Prices and incentives differ from US ones.
For plumbing company owners
An ageing heater is a predictable job, and many owners search for a plumber before it fails. To be the company they find, read plumber Google Business Profile and plumbing marketing plan. You can also book a call with LiveLeadsLane. LiveLeadsLane is a marketing practice for contractors, not a directory, and it does not take jobs or refer homeowners.
