Is Sydney water hard or soft?

Short answer: soft. Sydney Water puts Greater Sydney’s drinking water at about 57 mg/L of calcium carbonate, and anything under 60 mg/L counts as soft. That means most Sydney homes don’t need a water softener — here is what the numbers mean, how they vary by area, and what is actually worth filtering.

By the PH Water Filters installation team, Revesby Heights · Updated 25 October 2026

The short version

Five things worth knowing.

Sydney Water classes water under 60 mg/L of calcium carbonate as soft. Greater Sydney averages about 57 mg/L (Sydney Water).
Hardness varies a little by supply area, from roughly 30 mg/L in the south-west to the high 50s around Penrith.
There is no health limit for hardness. The Australian guideline of 200 mg/L is about scale in hot water systems.
Most Sydney homes do not need a water softener.
What people usually notice in Sydney water is the chlorine or chloramine taste, not hardness.

What hardness means

Calcium and magnesium, measured as calcium carbonate.

Hardness is the amount of dissolved calcium and magnesium in water, reported as milligrams per litre of calcium carbonate (mg/L CaCO₃). Hard water makes soap harder to lather and leaves scale in kettles and hot water systems. The Australian Drinking Water Guidelines describe it in bands:

Hardness (mg/L CaCO₃)	What the guidelines call it
Under 60	Soft but possibly corrosive
60–200	Good quality
200–500	Increasing scaling problems
Over 500	Severe scaling

Source: NHMRC, Hardness (as calcium carbonate) fact sheet. The guideline value of 200 mg/L is aesthetic — there is no health-based limit.

Sydney by area

How hard is the water in your suburb?

Sydney is supplied through several delivery systems, and hardness differs slightly between them. Sydney Water’s Potts Hill quarterly report (April–June 2025) recorded an average of 48.3 mg/L, with individual samples between 36 and 63 mg/L — so even the occasional reading just over 60 sits at the very bottom of the “good quality” band.

Supply area	Typical hardness	Example suburbs
Potts Hill	about 48 mg/L	Bankstown, Canterbury, Lidcombe
Prospect North	about 46–50 mg/L	Parramatta, Blacktown
Prospect South / East	about 50 mg/L	Liverpool, Fairfield, Chester Hill, Revesby Heights
Orchard Hills	about 57 mg/L	Penrith, St Marys
Nepean / Macarthur	about 30 mg/L	Camden, Oran Park

Area figures are approximate averages compiled by WaterScore from Sydney Water reports, and readings change from quarter to quarter. Every area is in the soft range.

So why is there scale on my kettle?

Soft isn’t the same as zero.

Soft water still carries some calcium. Each time a kettle boils, a little water evaporates and the minerals stay behind, so a light film builds up over months. In hard-water cities this happens in weeks. White spots on glass shower screens are usually dried minerals and soap residue rather than a sign of hard water. A rinse with diluted vinegar clears both.

Do you need a softener?

Usually not. Here is what to filter instead.

Chlorine or pool smell: Sydney Water disinfects with chlorine and, in many areas, chloramine. A carbon filter fixes taste at the kitchen tap — our 3 Stage Under-Sink is $299 installed.
Fluoride, lead or PFAS in drinking water: only reverse osmosis removes fluoride. Choose the six-stage at $649 or the ED600 tankless at $1,100.
Showers and every tap: whole house water filtration reduces chlorine and PFAS throughout the home. It is not a softener, and in Sydney it doesn’t need to be.
Want minerals in your drinking water: reverse osmosis removes most dissolved minerals, so our Stage 6 Balance and Alkafuse add calcium and magnesium back after the membrane.

Soft water and older pipes

“Possibly corrosive” — what that means at home.

The guidelines note that very soft water can be slightly more aggressive on metal pipes. Sydney Water manages pH and alkalinity to limit this, but older brass fittings and taps inside a home can still add traces of lead or copper when water sits overnight. Our guide to whether Sydney tap water is safe covers simple habits that help, and reverse osmosis reduces heavy metals at the drinking tap.