The quick answer, then the fine print.
Plan on replacing a conventional tank water heater every eight to twelve years. Many fail closer to the early end when they are never flushed, and a well-kept one can run longer. Tankless units are built to last longer than tanks, but they need descaling to get there.
Age is only the opening clue. A tank that is seven years old and leaking has reached its end. One that is eleven and quiet may still have time. The real question is the condition of the steel tank, and several signs tell you.
A timeline of what usually happens to a tank.
Years 1 to 5.
Most tanks run without drama. Sediment starts to settle, the anode rod begins to give up metal, and the heater adjusts quietly. This is the best time to flush the tank and look at the rod.
Years 6 to 9.
Scale thickens on the bottom, elements or burners work harder and the temperature and pressure relief valve may start to weep. Repairs become more common. This is when annual flushing pays off, if it has been done at all.
Year ten and up.
The anode rod is often spent, so corrosion moves to the tank lining. Small leaks at fittings appear, rust shows in the hot water, and the tank may make a rumble as scale cooks. Replacement stops being a question of if.
Signs it is time to replace, not repair.
Signs your water heater is near the end.
- Water pooling around the base, coming from the shell and not a fitting.
- Rust-colored or metallic-smelling hot water.
- Rumbling, popping or knocking from the tank.
- Heater age at or beyond ten years, from the serial number label.
- Less hot water than before, even after a repair.
- Repeated repair calls in a short period.
- Scale or flakes in the water when you drain a bucket.
A leak from the tank shell is the clearest of all. Once the glass lining cracks and the steel corrodes through, nothing patches it. Shut off the water supply to the heater, turn off power or the gas control, and call before a small leak becomes a flooded closet.
What actually ends a tank.
Three things work together to wear out a tank. Knowing them helps you stretch the life you have.
The anode rod.
Inside the tank hangs a rod, usually magnesium or aluminum, made to corrode instead of the steel. It is a sacrificial part. When it is gone, the tank lining becomes the next target. Checking and replacing the rod is one way to extend life, if the tank is still sound.
Sediment.
Minerals fall out of heated water and pile up on the tank floor. In a gas heater that layer sits between the burner and the water, so the steel overheats. In an electric heater it buries the lower element. Either way, it shortens life and wastes energy.
Temperature and pressure.
A tank run very hot ages faster, and water pressure spikes stress the shell. Thermal expansion in a closed system can push pressure high enough to weep at the relief valve. An expansion tank is a common answer, and a plumber can tell you if yours needs one.
Maintenance that actually helps.
| Task. | How often. | What it protects. |
|---|---|---|
| Flush a few gallons from the drain valve. | Once a year. | Slows sediment buildup. |
| Test the T&P relief valve. | Once a year. | Confirms it can discharge safely. |
| Inspect the anode rod. | Every few years. | Delays corrosion of the tank. |
| Check straps and connections. | Once a year. | Earthquake safety and leak catching. |
| Look for rust, damp and soot. | Every few months. | Catches trouble early. |
Be careful with the relief valve test and with an old drain valve. Corroded brass can break when turned, so call a plumber if it feels stuck.
Heater leaking or past ten years?.
Call the dispatcher for a same-day appointment when available and a plain answer on whether to replace.
Should you replace before it fails?.
Replacing on your schedule beats replacing at 2 a.m. with water on the floor. A planned swap lets you pick the fuel, the size and the location, and it avoids water damage. An emergency swap tends to reduce the choices to whatever can be installed fast.
If your heater is past ten years, has had a major repair, or is already leaking at fittings, start planning. A water heater replacement visit covers draining and removing the old unit, connecting the new one, setting the relief valve and discharge line, strapping, and testing. If you are changing the heater type, moving it, or adding a recirculation line, that moves into water heater installation with extra rough-in work.
Gas, electric or tankless when the time comes.
Replace like for like when the location and utilities are set up for it. Moving from a tank to tankless is a bigger decision: gas line capacity, venting, electrical needs and descaling all matter. A tankless model also costs more to install than a tank, though it takes up less floor space and does not hold a reservoir that can leak.
Size also matters. A tank sized for a household that has grown or shrunk will either run short or waste energy. Tell the plumber how many baths and how many people share the water.
Claremont water and your heater's lifespan.
Local note
Hardness and strapping in Claremont.
Golden State Water Company's 2026 Annual Water Quality Report, covering 2025 data, gives Claremont hardness as 97 to 330 mg/L as calcium carbonate, with an average of 190 mg/L. In grains per gallon that is 5.7 to 19, averaging about 11. Moderately hard to very hard water leaves scale in a tank, which is why a flush and an anode check matter here.
California Health and Safety Code section 19211 requires new and replacement residential water heaters, and existing ones, to be braced, anchored or strapped against earthquake movement. It applies to heaters up to 120 gallons with a pre-engineered strapping kit available. If you are unsure about local permit steps for a replacement, ask the Claremont Building Division at (909) 399-5477.
What makes a replacement cost more or less.
The tank itself is only part of it. Size and fuel type, the condition of the shutoff and venting, how far the unit sits from the water and gas or electric supply, and any upgrades the new unit needs all change the total. Haul-away of the old tank and the strapping kit belong in the quote too. Ask the plumber to list each item.
What to do if the tank is leaking now.
If water is pooling under the tank, close the cold supply valve above it and, for a gas unit, set the control to pilot or off if you can reach it safely. California Health and Safety Code section 19211 and the California Plumbing Code, built on the Uniform Plumbing Code (UPC), govern the replacement.
Water heater lifespan questions.
.
Most last about eight to twelve years. Water quality, whether the tank is flushed, how hot the setting is and the anode rod's condition all affect it. If yours is near 10 and has begun to rumble or leak, plan to replace it soon.
.
It can. Scale collects on elements and at the bottom of the tank, and a hardness average of about 11 grains per gallon in Claremont is enough to make a yearly flush worthwhile. Softening the water can also help.
.
Look at the label on the tank for the serial number. Many brands encode the month and year of manufacture in the first digits. If you cannot decode it, a plumber can read it and tell you the date.
.
Yes. State law under Health and Safety Code section 19211 calls for water heaters to be braced, anchored or strapped to resist earthquake movement. A plumber can check or add strapping when working on the unit.