Water is 98% of your cup of coffee. It's also the variable most home brewers never touch. The SCA recommends water between 75–150 ppm TDS (total dissolved solids) for specialty coffee brewing — but tap water across Australian cities ranges from soft Melbourne water at ~40 ppm to much harder Sydney water at ~80–100 ppm. Perth's desalinated water sits near zero. These differences affect extraction efficiency, flavour balance, and equipment scaling — and they're easy to address once you know what you're working with.
What TDS and hardness mean for your brew
TDS measures the concentration of dissolved minerals in water. Minerals — primarily magnesium and calcium — are what help water extract flavour compounds from coffee. Water that's too soft (low TDS) under-extracts, producing flat, lifeless coffee. Water that's too hard (high TDS) over-extracts and can produce harsh, chalky flavours, plus it scales your kettle and equipment faster.
The SCA target window (75–150 ppm) is achievable for most Australian brewers with minor adjustments.
Australian city water by the numbers
| City | Source | Est. TDS (ppm) | Hardness | Coffee verdict |
|---|---|---|---|---|
| Melbourne | Yarra catchment reservoirs | 30–50 | Very soft | Under-ideal — add minerals or use a remineralisation sachet |
| Sydney | Warragamba Dam | 80–110 | Moderate | Near-ideal range — mostly good as-is |
| Brisbane | Wivenhoe Dam | 60–90 | Moderate-soft | Good; varies by season |
| Adelaide | Murray River / desalination | 150–250 | Hard | Above ideal — filter recommended |
| Perth | Desalinated + groundwater | 30–80 | Variable | Desalinated sources are very soft — mineral addition helps |
| Hobart | Mt Wellington catchment | 25–40 | Very soft | Similar to Melbourne — remineralise |
Note: TDS figures are estimates based on published water quality reports. Your local council publishes an annual drinking water quality report with exact figures.
What to do about it
If your water is too soft (Melbourne, Hobart, Perth desalinated):
Use a remineralisation sachet or add a small amount of food-grade mineral concentrate to your filtered water. This is genuinely one of the highest-ROI changes a Melbourne home brewer can make.
If your water is near-ideal (Sydney, Brisbane):
Filter for chlorine and sediment (a Brita or similar), then brew. You're in the target window.
If your water is too hard (Adelaide, some Perth groundwater):
A reverse osmosis filter removes nearly all minerals, giving you a blank slate to remineralise. At minimum, use a filter pitcher with a hardness reduction cartridge.
The quick test: Boil your kettle. If you see white scaling on the element within a few weeks, your water is hard. If your coffee tastes flat regardless of grind or ratio, your water is probably too soft.
Water won't fix a bad grinder or a stale bag of coffee — but once everything else is dialled in, it's often the last variable standing between good coffee and exceptional coffee.
