This is the widest gap in Australian tap water. Melbourne’s eastern supply: 18 mg/L hardness, ~35 mg/L TDS. Adelaide metro: ~100 mg/L hardness, ~480 mg/L TDS. One city’s water needs almost nothing; the other makes the strongest case in the country for reverse osmosis.
Side-by-side data
All figures are from each utility’s own published water quality reporting — the same dataset behind our 8-capital water quality lookup.
| Measure | Melbourne | Adelaide |
|---|---|---|
| Hardness | 18 mg/L east; 25 west; ~108 outer | ~100 mg/L metro (70–115) |
| Total dissolved solids | ~35–40 mg/L | ~480 mg/L metro (280–510) |
| pH | ~7.4 | ~8.0 |
| Disinfectant | Chlorine (east); chloramine (west) | Chloramine |
| Fluoride | ~1.0 mg/L | ~0.56 mg/L |
| Source | Melbourne retailers, 2024–25 | SA Water, 2023–24 |
What Melbourne homes deal with
The luckiest tap water in the country, at least in the east: closed catchments, minimal mineral pickup, chlorine that a $40 carbon jug handles. The west’s chloramine and the outer corridors’ ~108 mg/L are the local exceptions to an otherwise easy story.
What Adelaide homes deal with
Hardness that scales appliances plus TDS that dominates flavour — the double burden no other capital carries at this level. It’s why Adelaide leads the country in filter adoption, and why RO (the only common technology that actually removes dissolved solids) earns its keep here like nowhere else.
Which filters, which city
Melbourne east: minimal — carbon for taste if you bother at all. Melbourne west: catalytic carbon. Adelaide: under-sink RO for drinking water is the transformative upgrade; whole-home scale management protects the hot water system on top.
See how every capital ranks in our hardest water in Australia ranking, or compare suppliers with the comparison tool.