A water heater is the appliance most likely to fail catastrophically, in the least convenient place, with the most water damage. It is also the one whose age almost nobody knows.
Typical lifespan
| Type | Expected life |
|---|---|
| Standard tank, gas | 8–12 years |
| Standard tank, electric | 10–15 years |
| Tankless | 15–20+ years |
| Heat pump / hybrid | 10–15 years |
Water quality moves these numbers more than anything else. Hard water can cut years off a tank. So can a heater that was never flushed, or one running at an unnecessarily high temperature.
How to find the age of yours
There is no install-date sticker, but the serial number encodes the manufacture date. Format varies by brand; most encode the year and week or month in the first four characters. Search for your brand’s serial decoder and you will find it.
Photograph the model plate while you are down there. You will want the model number when something fails, and the plate is usually in an awkward spot behind the tank.
Signs it is on the way out
Rusty or discolored hot water. If it is only on the hot side, the tank lining is failing. Not repairable.
Popping, rumbling, or knocking. Sediment has hardened on the bottom and water is boiling under it. This accelerates failure and wastes energy.
Moisture or rust around the base. Any weeping at the tank seam is terminal. Small leaks at fittings can often be tightened; leaks from the tank body cannot.
Not enough hot water anymore. Sediment displaces capacity. A tank that used to cover two showers and now covers one is telling you something.
It is past the expected life and you are on vacation next week. Age alone is a legitimate reason to replace on your schedule instead of its schedule.
Maintenance that actually extends life
Flush it annually. Connect a hose to the drain valve, shut off the cold supply and the power or gas, drain the tank, then refill. Thirty to forty-five minutes. If you have never done it and the tank is old, be aware that a long-unused drain valve sometimes fails to reseal, which is why this is better started as a habit early.
Check the anode rod every three to five years. It is a sacrificial rod that corrodes so the tank does not. Replacing a $30 rod at year five can add years to the tank. Most people have never heard of it.
Test the T&P relief valve annually. Lift the lever, let it discharge briefly, release. If it does not reseal or does not discharge, replace it. It is a safety device.
Set the temperature to 120°F. Hotter accelerates corrosion and scale, wastes energy, and creates a scald risk.
Add a drip pan and a leak sensor. A $25 water sensor next to the tank is the cheapest insurance in the house. Some policies discount for automatic shutoff valves.
All five of these belong on a recurring schedule rather than in your head. Our home maintenance reminder schedule covers the intervals, including the anode rod check that almost nobody remembers.
Replacement cost
| Scenario | Typical cost |
|---|---|
| Like-for-like tank, gas | $1,200–$2,200 |
| Like-for-like tank, electric | $1,000–$1,900 |
| Tank to tankless conversion | $3,000–$6,000 |
| Heat pump / hybrid | $2,000–$4,000 |
| DIY tank swap (materials only) | $550–$1,400 |
Prices include haul-away and a basic permit in most markets. Code upgrades such as an expansion tank, new venting, a pan and drain line, or seismic strapping commonly add a few hundred dollars and are not optional.
DIY is feasible for an experienced homeowner on an electric tank in an easy location. Gas involves combustion venting, which is where mistakes become dangerous. Many jurisdictions require a permit either way. If you are hiring it out, check licensing and insurance first.
Record the install date
The single most useful thing you can do is write down when it went in, what model, who installed it, what it cost, and when the warranty ends. That one entry answers every future question about this appliance, tells you when to start budgeting, and gives your insurer or buyer a documented history.
It is also how you find out that the tank that just failed was still under a six-year parts warranty.
That is exactly what HomeTrackIt is for: one entry per thing that happened, with the invoice, the permit and the model plate photo attached, and the annual flush already scheduled. Start a 30-day free trial, then $7 a month.
Common questions
How long does a water heater last?
A standard gas tank lasts 8 to 12 years and a standard electric tank 10 to 15. Tankless units run 15 to 20 or more, and heat pump or hybrid models 10 to 15. Water quality moves these numbers more than anything else: hard water, a tank that was never flushed, or a thermostat set too high all cut years off.
How do I find out how old my water heater is?
The serial number encodes the manufacture date. Most brands put the year and week or month in the first four characters, and your brand's serial decoder will translate it. Photograph the model plate while you are there, because you will want the model number when something fails.
What are the signs a water heater is failing?
Rusty hot water means the tank lining is going and cannot be repaired. Popping or rumbling means hardened sediment is trapping boiling water underneath. Weeping at the tank seam is terminal, though leaks at the fittings can often be tightened. Running out of hot water sooner than you used to is sediment displacing capacity.
What maintenance makes a water heater last longer?
Flush the tank annually, test the temperature and pressure relief valve annually, and check the anode rod every three to five years, since replacing a $30 rod at year five can add years to the tank. Set the temperature to 120 degrees Fahrenheit, and put a drip pan and a leak sensor underneath.
How much does it cost to replace a water heater?
A like-for-like gas tank runs $1,200 to $2,200 and electric $1,000 to $1,900. Tank to tankless is $3,000 to $6,000, heat pump or hybrid $2,000 to $4,000, and a do-it-yourself swap $550 to $1,400 in materials. Code upgrades such as an expansion tank, new venting or a pan and drain line commonly add a few hundred dollars and are not optional.
Can I replace a water heater myself?
On an electric tank in an easy location, an experienced homeowner can. Gas involves combustion venting, which is where mistakes become dangerous. Many jurisdictions require a permit either way.