We explain what causes a rotten-egg smell in your taps and what to check first. Hydrogen sulfide gas often forms when sulphur bacteria react inside a water heater or with an anode rod. Compare warm versus cold at a basin away from the sink to see if the issue is in the supply or the tank.
Simple at-home checks — baking soda and vinegar, a hot flush, or testing the tank — can rule out drain bacteria quickly. If the problem sits in the cylinder, flushing or disinfecting and inspecting the magnesium anode often fixes the smell.
We supply fast, professional plumbing across Melbourne, 24/7, using reputable parts and clear, affordable quotes. For urgent diagnosis and repairs, call our team on 1800 571 216 or see our hot unit service page at hot water repairs Burnside.
Key Takeaways
- Rotten-egg odour usually points to hydrogen sulfide from bacteria or anode reactions.
- Do a simple hot vs cold test away from the drain to find the source.
- Flushing and disinfecting the tank or changing the anode can remove the smell.
- Filtration helps when the supply is affected by contaminants.
- We offer 24/7 Melbourne plumbing for fast diagnosis and cost-effective repairs.
Why your hot water suddenly smells in Australian homes today
Heat speeds the release of sulphur gases, making the odour far more noticeable when you run a tap or shower.
In many homes the culprit is hydrogen sulfide gas produced by sulphur bacteria or by reactions involving a magnesium anode inside the water heater. Higher temperature lets trapped gas escape quickly, so the problem appears stronger from the hot tap.
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If both cold and hot taps smell, the supply or distribution system is a likely source. If only the hot tap smells, the heater or its anode is usually to blame.
- Stagnation after holidays or low temperature cycles can let bacteria grow and make the smell worse.
- Seasonal chemistry shifts, iron or manganese levels can also amplify odours.
- New installations sometimes smell until the anode stabilises; a material change may cure it.
If you need fast, 24/7 diagnosis and repairs across Melbourne, call us on 1800 571 216 for lasting, affordable fixes using quality parts.
| Probable source | Signs | Common fix |
|---|---|---|
| Water heater tank | Odour only from hot tap; stronger when warm | Flush tank; inspect/replace anode; shock disinfect |
| Incoming supply | Both taps smell; wide household impact | Filtration or contact supplier; test groundwater |
| New installation | Temporary sulphur scent after commissioning | Monitor; change anode material if persistent |
Smelly hot water
Identifying the exact odour helps decide the right fix.
Recognising the rotten egg odour versus other smells
A true rotten egg smell usually points to hydrogen sulphide. Other notes — musty, metallic or chlorine-like — suggest different contaminants or pipe issues.
Hot tap only or both taps? Quick checks to pinpoint the source
Pour cold and hot into separate clear glasses and take them away from the sink. Sniff each glass to see which one smells like rotten eggs.
If both glasses smell, the supply or distribution is likely. If only the hot glass smells, the heater or its anode is a prime suspect.
Is it safe to bathe or drink? Practical guidance for the home
Bathing and showering are generally fine. For drinking and cooking, use bottled supplies until testing rules out harmful contaminants.
To rule out a drain odour first, try 1/4 cup baking soda, 1/4 cup white vinegar; wait 10 minutes then flush with boiling water. If the smell persists across outlets or you see discolouration, it’s time to call for expert help.
We provide 24/7 testing and repairs across Melbourne. Call us on 1800 571 216 for fast, reliable service using reputable brands.
Common causes: bacteria, anode rods and hydrogen sulfide gas
Several household factors can combine to create that sulphur odour. Warm tank conditions, protective metal parts and changing supply chemistry all play a part. We outline the main causes so you can match symptoms to fixes.
Bacteria thriving in warm tanks
Sulphur bacteria can metabolise sulphates and produce hydrogen sulfide gas in warm cylinders. This process increases when temperatures fall and water sits unused.
Magnesium anode rod reactions
A magnesium anode protects the tank but can react in some chemistries and create a sulphur scent. New water heaters sometimes show this while the anode stabilises; changing anode material can help.
Stagnation, supply chemistry and distribution
Long periods of low use, cooler thermostat settings or holidays let bacteria multiply. If both taps and outlets smell, groundwater or the distribution system may be the source rather than the heater.
| Cause | How it generates gas | Common corrective action |
|---|---|---|
| Bacteria in tank | Metabolise sulphates → hydrogen sulfide | Flush, disinfect, raise temp temporarily |
| Anode reactions | Magnesium corrodes in some chemistries | Replace anode with suitable alloy (ATZ) |
| Supply chemistry | Iron/manganese and seasonal shifts amplify odour | Filtration or supplier testing |
If these causes match what you see at home, we can inspect, test and fix 24/7 across Melbourne using quality parts from reputable brands. Call 1800 571 216.
Step-by-step troubleshooting to find the source of the odour
Follow a clear sequence to pinpoint whether the issue is in your supply, the pipes or the heater.
Glass test: compare cold vs hot away from the sink
Fill two clear glasses — one cold, one hot — and sniff them away from the drain. If both samples smell like rotten eggs, the supply or system is likely at fault. If only the hot sample smells, target the water heater.
Rule out drain bacteria
Try 1/4 cup baking soda and 1/4 cup vinegar in the drain. Wait ten minutes, then flush with boiling liquid. This removes common biofilm odours near basins.
Isolate, flush and disinfect the heater
Drain a few litres, then perform a full flush to remove sediment that harbours bacteria. For persistent issues, shock the tank with hydrogen peroxide or a diluted bleach solution, then flush thoroughly.
Inspect the anode rod and adjust temperature
Check the anode rod for heavy corrosion or magnesium type. Replacing with an ATZ alloy often reduces a smell like rotten eggs. A cautious temperature raise can curb bacteria but follow manufacturer guidance to avoid scald risks.
If DIY steps don’t resolve the problem, we offer same-day 24/7 callouts across Melbourne using reputable-brand parts. Call 1800 571 216 or see our hot water repairs Sunshine North.
Treatment options and long-term solutions
Long-term relief comes from the right combination of anode upgrades, filters and regular tank care.
Replace the anode rod with ATZ alloy
We often replace a magnesium anode with an ATZ (aluminium/tin/zinc) anode rod to curb sulfur odours while keeping tank protection.
An ATZ anode typically reduces reactions that produce hydrogen sulfide gas without shortening the life of the water heater.
Whole-home filtration
For supply issues we recommend iron filters or carbon systems at the point of entry. These filter types cut iron and chlorine that can worsen an odour or taste.
Reverse osmosis for drinking
Reverse osmosis is a targeted solution at the kitchen tap. It gives odour-free, great-tasting drinking water from a single outlet.
Preventive maintenance
Routine flushing, periodic anode inspection and sensible temperature management stop bacteria and sediment from returning.
- We assess chemistry and specify the right anode rod (often ATZ).
- We install and service filtration systems and RO units as needed.
- We set maintenance plans and use reputable-brand parts to keep costs clear.
Call OnCall Emergency Plumbers in Melbourne 24/7 on 1800 571 216 for diagnosis and repairs.
Why choose OnCall Emergency Plumbers for smelly hot water issues
A lingering scent from the tap needs fast diagnosis to find whether the issue is in the supply, the heater or nearby pipes.
Rapid 24/7 emergency response across Melbourne
We provide a rapid, 24/7 response across Melbourne to resolve hot water odour problems before they disrupt your routine.
Experienced professionals and quality materials
We diagnose whether the source is a water heater, the incoming supply or localised biofilm in pipes.
Our teams use reputable-brand parts and stock anode rod and anode alloy options to suit local chemistry.
Cost-effective repairs and full plumbing support
- We balance immediate relief from the smell with long-term system protection.
- We handle anode rod replacement, shock disinfection, leak fixes and blocked drains.
- We follow a clear troubleshooting framework so you understand the problem and options.
Trusted across homes and industries
We tailor solutions to usage patterns and compliance needs. For priority booking or emergency dispatch, call 1800 571 216.
| Service | Benefit | Typical response |
|---|---|---|
| Anode rod replacement | Reduces odour, protects the tank | Same-day supply and fit |
| Shock disinfection | Removes bacterial source | Rapid on-site treatment |
| Full plumbing repairs | Fixes leaks, blocked pipes and system faults | Priority 24/7 callouts |
Conclusion
A quick glass test and targeted flushing usually show whether the smelly hot water comes from the tap or the cylinder.
Most cases trace to hydrogen sulfide produced by bacteria or reactions at the anode rod. Simple fixes — flush and disinfect, adjust temperature safely, or fit an ATZ anode — often remove the rotten egg smell.
When the supply contributes, filtration or a point-of-use RO unit improves taste and removes sulphur compounds. Bathing is generally safe, but avoid drinking until testing confirms safety.
For fast, affordable diagnosis and repairs across Melbourne call 1800 571 216. We’re available 24/7, use reputable-brand parts and can inspect your hot water repairs Southbank needs on the spot.
