Discoloured, rusty, or smelly hot water is one of the most alarming things a Melbourne homeowner can encounter from the tap. The good news: there are specific causes and specific fixes, and most situations can be resolved.
Why Is My Hot Water Rusty or Discoloured?
Rusty or brown hot water is almost always caused by internal corrosion of the hot water storage tank. This occurs when the sacrificial anode rod — a magnesium or aluminium rod inside the tank that protects the steel walls from rust — has been depleted. Once the anode is gone, the tank steel begins to corrode, releasing rust particles into the water.
If the discolouration is only in the hot water (not the cold), the tank is the source. If both hot and cold water are discoloured, the issue is with the supply pipework or the mains supply.
Why Does My Hot Water Smell?
A rotten egg or sulphur smell in hot water is caused by hydrogen sulphide gas, produced by a reaction between a magnesium anode rod and certain water chemistry (particularly water with high sulphate content). The smell is most pronounced after the system has been off or unused for a period. Solutions include replacing the magnesium anode with an aluminium anode, flushing and treating the tank, or raising the water temperature to 60°C+ (which kills the sulphate-reducing bacteria that catalyse the reaction).
Sediment Build-Up in the Tank
Over years of operation, calcium and magnesium minerals in Melbourne’s water supply (Melbourne water is relatively soft but not pure) precipitate out and settle at the bottom of the hot water tank as sediment. Symptoms include reduced capacity, longer recovery times, knocking or rumbling sounds from the tank as water heats through the sediment layer, and reduced efficiency. Flushing the tank by opening the drain valve and allowing sediment to discharge resolves mild cases. Severe sediment accumulation in older tanks is a sign the system is approaching end of life.
Anode Replacement: The Preventive Fix
Replacing the anode rod every 5 years is the most important maintenance action for hot water storage systems. A new anode costs $80-$150 for the part; plumber labour to access and replace it is $150-$250 on top. This $250-$400 maintenance spend every 5 years can extend system life from 8 years to 15+ years and prevents the discolouration and odour problems described above. Many Melbourne homeowners have never heard of anode replacement — which is why so many hot water systems fail prematurely.
When to Replace vs Flush or Service
If rusty water has appeared and the system is over 10 years old, the tank is likely corroded internally and replacement is the practical solution — a corroded tank cannot be repaired. If the system is under 8 years old, an anode replacement and tank flush may resolve the issue. If smell without discolouration is the issue, an anode replacement and treatment is almost always effective regardless of system age.
Sedcon Plumbing — Hot Water Service Across Melbourne
We diagnose hot water quality issues, replace anodes, flush tanks, and replace systems across Melbourne. Call 0468 013 012 for a fast diagnosis.