Wellington
Wellington, New Zealand has an estimated water hardness of 34 ppm (mg/L as calcium carbonate), which is classed as soft. Low scale risk. Use the lower end of detergent guidance.
Wellington water hardness in every unit
| Unit | Reference estimate |
|---|---|
| mg/L or ppm (CaCO₃) | 34 |
| mmol/L | 0.34 |
| German degrees (°dH) | 1.9 |
| French degrees (°fH) | 3.4 |
| Clark degrees (°e) | 2.39 |
| Grains per US gallon (gpg) | 1.99 |
Published range: 18–47 ppm.
How the Wellington figure was derived
- Period covered: 2018-07-01 – 2019-06-30
- Calculation: The average is the simple, unweighted mean of the published values for 3 treatment plants. The range runs from the lowest to the highest of those values.
Where Wellington's water comes from
- Supplier: Wellington Water, on behalf of the councils of Wellington, Hutt, Porirua and Upper Hutt
- Source: The Te Mārua, Wainuiomata and Waterloo/Gear Island treatment plants
- Official website: Wellington Water
Wellington Water’s 2018/19 treated-water means were 18 mg/L at Te Mārua, 36 mg/L at Wainuiomata and 47 mg/L at Waterloo/Gear Island, all soft (under 100 mg/L). Wellington Water: hard or soft? (checked 2026-10-31).
Hardness by supply zone in Wellington
| Supply zone | ppm |
|---|---|
| Te Mārua | 18 |
| Wainuiomata | 36 |
| Waterloo/Gear Island | 47 |
How Wellington compares
With a reference estimate of 34 ppm, Wellington ranks 54th hardest of the 69 cities in our directory, 40 ppm below the directory median of 74 ppm. Among the cities in our directory in Oceania, Brisbane is the hardest at 117 ppm and Tauranga is the softest at 10 ppm.
What the range means
Published figures for Wellington run from 18 to 47 ppm. The spread is relatively narrow (29 ppm), so the average is a reasonable guide, though your own tap can still differ from the citywide figure.
What soft water means at home
Soft water rarely leaves visible scale. Kettles, taps and shower screens stay clearer for longer, and detergents lather easily, so the main risk is overdosing. Start at the minimum amount on the pack and increase only if results are poor.
Using a 34 ppm reading with your appliances
- Dishwasher: salt check manual; match the converted reading to your model. Use salt only as specified for the built-in softener.
- Coffee machine: descale when the manual or machine indicates; filter: use only a compatible filter specified by the manufacturer.
- Laundry: use the soft-water dose. Start at the label minimum and adjust for soil level.
- Kettle: Inspect for scale; follow the manual.
- Humidifier: For ultrasonic or impeller units, use low-mineral water such as distilled water. Empty and dry portable tanks daily; clean every third day. Follow manufacturer instructions.
Official manufacturer guidance
Use these references with your exact appliance model. They explain settings and maintenance, not the local water measurement. Source languages and model limits are shown; these are not affiliate links.
- Fisher & Paykel New Zealand — DW60U dishwasher user guide: water hardness and dishwashing (en-NZ)
Explains how hard water affects dishwashing and advises fitting a household water softener if your home’s hardness is above 250 ppm (14.6 gpg). Check the guide for your exact model.
(checked 2026-10-20).
Hardness alone does not determine maintenance frequency. How to match your reading to an appliance manual. Dishwasher settings by brand: find your setting. Thinking about a softener? Pros and cons and sizing. Kettles and coffee machines: descaling guide. Portable humidifier care: US EPA guidance.
Frequently asked questions
Do I need dishwasher salt in Wellington?
Check manual. Use salt only as specified for the built-in softener. Always follow your dishwasher manual.
How often should I descale a coffee machine in Wellington?
Descale when the manual or machine indicates. Hardness alone does not determine an interval: usage and appliance design also matter. Water filter: use only a compatible filter specified by the manufacturer.
Do I need a water softener in Wellington?
Almost certainly not. Soft water does not usually justify a softener.
Is hard water in Wellington safe to drink?
Water hardness is mainly an aesthetic and scale issue. The World Health Organization does not set a health-based guideline value for it. Hardness affects taste, scale and detergent use rather than drinking safety, and your utility is responsible for meeting drinking-water standards. If you have a specific health or dietary concern, ask your doctor.
How to check your own water
City averages are a starting point. To get your actual figure, check the linked source (Wellington Water: hard or soft?) and obtain a current report for your address from your water supplier, or dip a hardness test strip in a glass of cold tap water and read it against the chart. Strips usually report in °dH, gpg or ppm; enter the number into the Waterdial checker to convert it and see the matching appliance settings. Use a recent, correctly performed hardness test when a city estimate is too broad.
Source
Wellington Water: hard or soft?, checked 2026-10-31. Guidance is general; your appliance manual takes priority.
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