How Long Does a Hot Water System Last?

Hot water systems rarely fail at a convenient time, so it helps to know roughly how much life yours has left. How long does a hot water system last? The short answer for a storage tank is typically around 8 to 12 years, but the type of system, the water it heats and how well it has been looked after all move that number.

Below are typical lifespans by type, what wears a system out, the signs it's near the end, and how to weigh up repair against replacement. The figures come from government energy guides and manufacturers' own guidance, so read them as ranges, not promises.

Typical lifespan by type of hot water system

Each type ages differently, and published figures vary. Solar Victoria says hot water systems typically last 8 to 10 years, while one major manufacturer's US site puts traditional tanks at 8 to 12 years. Your owner's manual sets out the service schedule for your own model.

• Electric storage: typically 8 to 12 years. A leaking tank usually means replacement, so the tank warranty is a useful clue to design life: the Your Home guide to hot water systems says tank warranties are typically 5 to 10 years for glass-lined steel and 10 to 15 years for stainless steel.
• Gas storage: also a storage tank, so expect a similar range; the tank warranty figures above apply to storage tanks generally.
• Continuous flow: there's no storage tank to corrode, and one manufacturer's US site puts tankless units at 15 to 20 years or more with proper care.
• Heat pump: about 10 to 15 years, according to one manufacturer's US maintenance guide. Solar Victoria suggests looking for a warranty of at least 5 years and checking that prompt service is available in your area.
• Solar: one council guide says a solar hot water system should last around 15 to 20 years if it's serviced at the recommended intervals. Solar Victoria notes that tanks and collector panels are generally warranted for five to ten years, with valve work covered for 12 months.

What wears a hot water system out

Storage tanks wear from the inside. Your Home explains that most are steel with a glass-enamel lining, and glass-lined tanks have a sacrificial anode, a rod fitted to reduce tank corrosion. The anode needs replacing every few years; once it's used up, the tank itself starts to corrode. Stainless steel tanks don't need one.

Water quality

The water you heat matters. Your Home says stainless steel tanks aren't suitable in hard water areas, where the water carries a high level of dissolved minerals, and glass-lined tanks there may need a different type of anode. One Australian electric storage manual brings its major service forward from every five years to every three where total dissolved solids exceed 600 mg/L. Solar Victoria adds that some warranties are conditional on water quality.

Skipped servicing

Manufacturers publish service schedules for a reason. One Australian electric storage manual says regular servicing helps extend the life of the water heater, and lists a five-year service by a licensed tradesperson: replace the pressure and temperature relief (PTR) valve, replace the anode, inspect and flush the expansion control valve if one is fitted, and drain and flush the tank. A gas continuous flow owner's guide asks for a service by an authorised person at intervals of no more than 2 years.

The same electric storage manual asks owners to lift the relief valve's easing lever for about 10 seconds every six months, standing clear of the drain outlet, and warns that not doing so may result in the heater exploding. Check your own manual before trying it, as models differ.

Signs your hot water system is near the end

Some faults are routine repairs; others suggest the tank is finished. Manufacturers and government guides point to these warning signs:

• Water leaking from the base of the tank. If the leak is from the tank itself, replacement is usually required, while small valve or fitting leaks may be repairable.
• Rusty or discoloured hot water. It's listed as a sign of a failing unit, but it isn't always the heater: our guide to brown hot water covers other causes.
• Rumbling or popping noises, which can come from hardened sediment on the tank floor.
• A relief valve that won't stop running. Some dripping during heating is normal, but continuous leakage may indicate a problem. Your Home's rule of thumb: if a bucket under the valve fills in a day, the valve needs replacing.
• Age plus repeat faults. One manufacturer's US site says a unit that's 10 to 15 or more years old and having recurring issues is a strong signal on its own.

How to tell how old your system is

Solar Victoria says you can check the age of your system on the manufacturer's sticker, normally on the upper part of the unit, and suggests replacing pre-emptively rather than waiting until it's too late. If you have no hot water at all, work through how to troubleshoot no hot water before assuming the worst.

Should you repair or replace it?

Plenty of faults are worth fixing. Elements, thermostats and anodes are designed to be swapped out, and one manufacturer's US rule of thumb is that repair makes sense when the unit is under 6 to 8 years old, shows no tank corrosion or structural leaks, and the repair costs well under half the price of a new unit.

Replacement is usually the better path when the tank itself is leaking or corroded, or an older system keeps failing. Your Home's advice is to look at your options while an ageing system still works, because you may not have much time to decide when it fails. That also gives you room to consider a different type, and our comparisons of gas and electric systems and tankless versus storage units are a good place to start.

If your system is leaking, noisy or running cold, call us on 0411 251 759. With our hot water repairs you'll get fully qualified advice and a free plumbing safety report, so you'll know whether a repair is worth it, and if it isn't, we can talk you through hot water installation and replacement.