How do I know if my hot water system needs replacing?

Key indicators: the system is over 10 years old (gas storage) or 12 years old (electric); rust-coloured hot water; water pooling at the base of the tank; the pressure relief valve is regularly releasing; hot water runs out faster than before; or the unit is making unusual rumbling or popping sounds.

Is it better to repair or replace a hot water system?

Generally, if a gas storage system is over 8 years old and the repair cost exceeds $500, replacement is more economical. Replacing gives you a new warranty and the opportunity to upgrade to a more efficient system. A plumber can give you an honest assessment on site.

What is the lifespan of a hot water system in Melbourne?

Gas storage systems last 10-12 years on average. Electric storage systems last 10-15 years. Gas continuous flow systems last 15-20 years. Heat pump systems last 10-15 years. Regular servicing can extend lifespan; hard water areas may see shorter lifespans.

How to Tell How Old Your Hot Water System Is (And When to Replace It)

Hot water systems don’t send warning notices. They work fine for years, then fail — usually on a cold Melbourne morning. Knowing how old your system is and when it’s likely to fail lets you replace it on your terms rather than in a crisis.

How to Find Your Hot Water System’s Age

Every hot water system has a data plate — a metal or sticker label on the side, front, or behind an access panel. Most brands show the manufacture date directly. For Rheem and similar brands, the serial number encodes it: the first two digits are the year, the next two the week. Serial number starting with 1427 = manufactured in the 27th week of 2014.

Expected Lifespans by System Type

System Type	Expected Lifespan
Gas storage (Rheem, Rinnai, Dux)	8–12 years
Gas continuous flow	15–20 years
Electric storage	8–12 years
Heat pump	10–15 years
Solar with electric booster	15–20 years

Signs Your Hot Water System Is Nearing the End

Age alone — if past its expected lifespan, plan for replacement. Rusty or discoloured water — corrosion inside the tank. Water pooling under the unit — water coming from the tank body means the tank is corroding internally; replace it. Inconsistent temperature — heating element or burner issues. Rumbling or popping sounds — sediment buildup. Long wait for hot water — the system is losing efficiency.

Replace or Repair?

A useful rule of thumb: if the system is more than 70% through its expected lifespan and needs a significant repair, replace it. When you replace, consider upgrading to a heat pump system — Victorian government rebates (VEU program) currently offer up to $1,000 off the cost, and running costs are 60–70% lower than conventional electric.

Property Managers

A hot water failure in a rental property is an urgent repair under Victorian tenancy law — must be attended within 24 hours. Planning replacements proactively means scheduled downtime rather than emergency call-outs and tenant disputes. Sedcon Plumbing can assist with portfolio-wide hot water system audits across Melbourne. Contact us →

Hot water system past its use-by date? Call 0468 013 012 — we install all types of hot water systems across Melbourne, often same-day. See our hot water service →

Learn more about our Hot Water Repairs Melbourne service, or see all suburbs we cover across greater Melbourne.