Johannesburg
Johannesburg, South Africa has an estimated water hardness of 85 ppm (mg/L as calcium carbonate), which is classed as moderately hard. Some mineral build-up is possible in heated appliances.
Johannesburg water hardness in every unit
| Unit | Average |
|---|---|
| mg/L or ppm (CaCO₃) | 85 |
| mmol/L | 0.85 |
| German degrees (°dH) | 4.76 |
| French degrees (°fH) | 8.5 |
| Clark degrees (°e) | 5.96 |
| Grains per US gallon (gpg) | 4.97 |
Published range: 60–110 ppm.
Where Johannesburg's water comes from
- Supplier: Johannesburg Water, which buys treated water from Rand Water
- Source: Raw water from the Integrated Vaal River System (mainly the Vaal Dam), treated by Rand Water
Rand Water treats and sells water to Johannesburg, Pretoria and other Gauteng municipalities. South African Government: Rand Water and Gauteng water supply (checked 2026-10-05).
How Johannesburg compares
With an average of 85 ppm, Johannesburg ranks 7th hardest of the 19 cities in our directory, 19 ppm above the directory median of 66 ppm. Among the cities in our directory in Africa, Cape Town is the softest at 45 ppm.
What the range means
Published figures for Johannesburg run from 60 to 110 ppm. The spread is relatively narrow (50 ppm), so the average is a reasonable guide, though your own tap can still differ from the citywide figure.
What moderately hard water means at home
Moderately hard water can leave light white deposits on kettle elements, taps and glassware over time. It is usually manageable with periodic descaling, and many households need no softening equipment at all.
Appliance settings for 85 ppm water
- Dishwasher: salt optional; low–medium hardness band. Use salt if you see spotting or your manual requires it.
- Coffee machine: descale every 2–3 months; filter: helpful for taste and scale control.
- Laundry: use the medium-water dose. Follow the product label for your load size.
- Kettle: descale inspect every 6–8 weeks.
- Humidifier: filtered water can reduce white dust; clean at least weekly.
Frequently asked questions
How hard is the water in Johannesburg?
The estimate for Johannesburg, South Africa is about 85 mg/L as calcium carbonate (4.76 °dH, 8.5 °fH, 4.97 gpg), with a published range of 60–110 mg/L. That is classed as moderately hard water. Regional treated-water estimate.
Do I need dishwasher salt in Johannesburg?
Optionally. Use salt if you see spotting or your manual requires it. Always follow your dishwasher manual.
How often should I descale a coffee machine in Johannesburg?
At this hardness, descale every 2–3 months. Water filter: helpful for taste and scale control.
Do I need a water softener in Johannesburg?
Usually not. Appliance settings and occasional descaling are normally enough, but a filter or softener is a personal choice if you dislike spotting.
Is hard water in Johannesburg 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.
Who supplies tap water in Johannesburg?
Johannesburg Water, which buys treated water from Rand Water. Source: Raw water from the Integrated Vaal River System (mainly the Vaal Dam), treated by Rand Water.
How to check your own water
City averages are a starting point. To get your actual figure, look for the latest water-quality report from Rand Water quality or your local 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. A manual reading always beats a city estimate.
Source
Rand Water quality, checked 2026-10-05. Guidance is general; your appliance manual takes priority.
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