Hot Water System Maintenance Tips for Melbourne Homes, What Actually Matters

Alister here, owner of Prime Plumbing & Gasfitting. Hot water failures are some of the most disruptive jobs we attend, a flooded laundry from a perforated tank, a cold shower on a winter morning when the TPR finally gave up, a pilot that won’t relight after a power flicker. Most of it is preventable. This guide covers the maintenance that actually matters in Victorian conditions, what’s safe for a homeowner to do, and what has to be a licensed job.

What you’re dealing with, Melbourne specifics

Melbourne tap water is unusually soft compared to most Australian capitals. Catchment water through Yan Yean, Sugarloaf and Cardinia averages around 30 mg/L total hardness (as CaCO₃), versus 100-300 mg/L in places like Adelaide. Soft water is gentle on heat exchangers but it’s actually more aggressive on sacrificial anode rods, because anode protection relies on ion exchange and soft water sets up a stronger galvanic couple. Practically: anode rods in Melbourne tanks often need replacement on the earlier end of the manufacturer’s 5-year guidance, not the late end.

To date your unit, look for the data plate (usually a stainless rectangle near the inlet pipework). Rheem and Rinnai serial numbers encode the manufacture year. If the unit is over 10 years old it’s worth budgeting for replacement rather than chasing repairs.

The maintenance that’s actually worth doing

Temperature and pressure relief (TPR) valve, annual flick test

The TPR is the only mechanical safety device on a storage hot water tank. Without it functioning, an overheating tank can fail catastrophically. AS 3500.4 requires the TPR to discharge through a fixed copper drain line (not flex hose) to a safe location.

Test annually: lift the lever halfway, hear water discharge, release, water stops. If water keeps dripping after release, the valve is fouled or worn and needs replacement, that’s a licensed plumber job because the tank has to be isolated and partially drained. If you don’t hear or see water on the lift, the valve is seized, also replacement.

One trap: if the TPR weeps continuously every time the burner relights or the element cycles, the problem is usually NOT the TPR, it’s water expansion in a closed system. Modern non-return valves on the cold inlet trap thermal expansion, the pressure climbs, and the TPR does its job and bleeds. The actual fix is fitting an expansion control valve, not replacing the TPR. This misdiagnosis is common, checking the pressure relief weep history before condemning the TPR saves replacing a good valve.

Anode rod, inspect at the 5-year mark, replace at the 7-year mark

The anode rod is a magnesium or aluminium-zinc bar that screws into the top of the tank. It corrodes preferentially so the steel tank doesn’t. Once the anode is consumed the tank starts rusting from the inside, and there’s typically no warning until the bottom drops out and you have a flooded laundry.

For Melbourne soft water, magnesium anodes deplete faster than the standard schedule. Pulling the anode at the 5-year mark for a look is reasonable, if there’s clean steel core showing through more than half the length, replace it. Aluminium-zinc anodes (also called “alloy anodes”) last longer in soft water and are worth the upgrade at replacement time.

Anode inspection requires a long socket wrench, sometimes 600+ Nm of torque to break the seal, and clearance above the tank to lift the anode straight up. In typical Melbourne ceiling-cupboard or compact-laundry installations there’s often not enough head room and the rod has to be cut and re-installed in flexible segments. That’s a licensed job.

Visual inspections you can do safely

• Rust streaks down the side of the tank: anode is finished. Replace the anode (or the unit) before the tank perforates.
• Wet area around the base: tank wall has perforated. Replacement is the only fix, don’t chase the leak with sealants.
• Yellow flame on a gas heater (visible through the inspection window): incomplete combustion, often a flue blockage. Stop using the unit and call a licensed gasfitter, carbon monoxide risk.
• Pilot light keeps going out: thermocouple wear or flue draft issue. Licensed gasfitter job.
• Noises during heat cycle: rumbling = sediment buildup on the bottom of an electric tank (the element is heating a sludge layer). Banging on gas storage = expansion-relief issue (see TPR section above).

Tank flushing

Tank flushing has limited value on Melbourne water, soft water means low scale, low sediment. Annual flushing isn’t routinely needed here. If you’re hearing rumbling on an old electric tank, flushing can buy you time before replacement, but if the noise is there the tank is already late in its life.

If you do flush, follow the manufacturer’s procedure exactly, uncontrolled cold-water inrush into a hot tank can crack the porcelain lining.

Thermostat and temperature settings, Victorian regulation

AS/NZS 3498 requires the storage tank to be set to a minimum of 60°C to prevent Legionella growth. Outlet temperature to bathroom basins, showers and baths must not exceed 50°C, which is achieved with a tempering valve (TMV) on the hot outlet. Kitchen and laundry outlets are not regulated for temperature.

Don’t set the storage thermostat below 60°C to “save energy”, it’s a Legionella risk. Save energy by improving insulation and reducing pipework run length, not by lowering storage temperature.

What counts as licensed work in Victoria

Per the Plumbing Regulations 2018, hot water unit installation, replacement, relocation, and disconnection are all licensed plumbing work. So is any pressure-side work, anode replacement, TPR replacement, expansion-valve fitting. Compliance Certificates are required by law for plumbing work valued over $750, and they’re issued as standard practice for any compliant licensed work regardless of dollar value. Insurers and conveyancers commonly ask for these on house sale.

Homeowner-safe maintenance is restricted to: visual inspection, listening for noises, checking the data plate for age, isolating the unit if you find a leak (gas valve or electrical breaker, then cold water inlet), and photographing the unit for a quote.

When the unit’s near end-of-life

Industry-typical lifespans in Victorian conditions:

• Gas storage (Rheem / Rinnai / Aquamax): 8-12 years
• Electric storage: 10-15 years
• Heat pump (Sanden / Reclaim / Stiebel Eltron): 10-15 years on the tank, 7-10 on the compressor
• Instantaneous gas (Rinnai Infinity / Rheem Continuous): 15-20 years

If your unit is in the last quarter of its expected life and you start seeing rust streaks, intermittent hot water, or the anode has never been touched, planning a replacement beats waiting for the failure call. A planned replacement with a new Compliance Certificate (and, where applicable, the Victorian Energy Upgrades rebate for electric-to-heat-pump conversions) is typically cheaper than an emergency call-out plus water-damage cleanup.

Want a check-over?

Prime Plumbing & Gasfitting offer paid hot-water inspections, anode pull, TPR test, gasfitter visual on gas units, data-plate age check, written notes for your records. Call 0475 407 670 or use the hot-water inspection request form. Tell us the unit brand, model, age (or “unknown”), location (cupboard / laundry / outside / roof), and whether it’s gas or electric, saves a call back.

, Alister, Prime Plumbing & Gasfitting

Related reading

• Why hot water is costing you more, a plumber’s diagnostic guide
• When to replace a hot water system
• Hot water system replacement Melbourne: costs, types & 2026 guide