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Water Hardness
Information about water hardness and how to reduce it at home
All of Auckland’s drinking water sources – dams, rivers, streams and underground aquifers – have different mineral compositions. This mineral content depends on the water’s journey from where it falls as rain to the place where we abstract it and treat it to make it safe to drink.
The mineral content of water stored in dams or abstracted from rivers is quite different from what we see in groundwater sources. Groundwater typically contains higher levels of naturally occurring minerals because of the path it takes through various layers of soil, rock and shell beds before it gets to our bores or wells, where it is extracted for treatment. The water picks up the minerals as it moves through the aquifer.
Minerals typically found in water include calcium, magnesium, sodium carbonates, silica, iron and manganese. The higher calcium, magnesium – and sometimes sodium – content means groundwater is often considered ‘harder’ than other drinking water sources.
About a third of the water used in New Zealand comes from groundwater sources.
Auckland’s groundwater sources fall in the ‘soft’ or ‘moderately hard’ category and are well within the recommended range stated in the New Zealand Drinking Water Standards. This range is based on guidance from the World Health Organisation.
While naturally occurring, these minerals can build up on domestic appliances and smooth surfaces in the form of ‘scale’. The scale may contain one or a combination of several compounds like calcium carbonate or silica. It may appear on shower doors and tapware, or in kettles and hot water systems.
Frequently asked questions
Frequently asked questions
Can I reduce water hardness at home?If you prefer your water to be soft, you may want to consider installing a domestic water softener that’s designed to remove both calcium and silica. There are many different systems available in New Zealand from a variety of suppliers. You would need to engage a plumber to install a softening device.
If you do install a water softener, we recommend you leave your kitchen tap unsoftened for drinking water as softeners can add higher levels of sodium to the water.
If you prefer your water to be soft, you may want to consider installing a domestic water softener that’s designed to remove both calcium and silica. There are many different systems available in New Zealand from a variety of suppliers. You would need to engage a plumber to install a softening device.
If you do install a water softener, we recommend you leave your kitchen tap unsoftened for drinking water as softeners can add higher levels of sodium to the water.
How can I reduce the formation of scale in my house?If you would rather not install a water softener, the best way to prevent silica scaling is to dry surfaces like shower doors before the water evaporates. It can also be cleaned with a mildly abrasive glass cleaner. Scale in dishwashers and hot water cylinders can be reduced by lowering the temperature of your hot water system.
Please check with your dishwasher or washing machine manufacturer before adding any products to remove scaling.
If you would rather not install a water softener, the best way to prevent silica scaling is to dry surfaces like shower doors before the water evaporates. It can also be cleaned with a mildly abrasive glass cleaner. Scale in dishwashers and hot water cylinders can be reduced by lowering the temperature of your hot water system.
Please check with your dishwasher or washing machine manufacturer before adding any products to remove scaling.
How can I remove limescale? - One way to descale your kettle is to half-fill it with a solution of equal parts water and white vinegar. Boil the mixture and then let it sit in the kettle for about 15 minutes. Pour it out and then rinse it thoroughly.
- To clean your showerhead, fill a plastic bag with vinegar and tie it over the showerhead so it is submerged. Leave it like this overnight and then remove the bag. If your showerhead is removable, you can just submerge the showerhead in a bowl of vinegar.
- One way to descale your kettle is to half-fill it with a solution of equal parts water and white vinegar. Boil the mixture and then let it sit in the kettle for about 15 minutes. Pour it out and then rinse it thoroughly.
- To clean your showerhead, fill a plastic bag with vinegar and tie it over the showerhead so it is submerged. Leave it like this overnight and then remove the bag. If your showerhead is removable, you can just submerge the showerhead in a bowl of vinegar.