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Some areas in WA have 'hard' water, particularly if the water comes from groundwater supplies.

Hardness is a measure of the concentration of calcium and magnesium salts in water.

Calcium and magnesium are common in many supplies across WA. These natural minerals are dissolved as water moves through soil and rock and cannot be removed by filtration. The degree of hardness becomes greater as calcium and magnesium content increases.

The Australian drinking Water Guidelines define elevated hardness as 200 milligrams of calcium and magnesium salts per litre of water.

Ongoing tests confirm that the water we supply to customers meets all health guidelines and is safe to drink.

What causes it?

Hard water is caused by a higher than usual concentration of calcium and magnesium salts in water.

What happens?

Hard water may leave spots on drinking glasses, shower screens or garden plants because the minerals remain after the water has evaporated.

Hard water also reacts chemically with soap. The higher the hardness, the more soap is required to form a lather.

Some appliances such as dishwashers come with suggestions on how to manage the effects of hard water so it’s a good idea to check your water hardness.

How do I know if you have hard water?

The Perth Metropolitan Water Supply Scheme, supplied by surface water, desalinated water and some groundwater meets the national guidelines for hardness levels.

Country customers are more likely to experience hard water because they are supplied primarily by groundwater sources.

You can find out how hard the water in your area is by calling our Faults, Emergencies and Security line on 13 13 75.

What to do

Calcium staining

To avoid spots caused by hard water, use liquid soaps and dry wet surfaces immediately after water use. You can also use cleaning products that remove calcium and lime deposits, scale and discolouration from bench tops, appliances, toilets, sinks, bathtubs, tiles and glass.

Use bicarbonate soda and vinegar-based cleaning products to clean domestic appliances making sure to rinse thoroughly before use.


If you are installing a new dishwasher you should find out if your area has hard water. If it does consider a dishwasher that is suited to hard water and use the recommended dishwashing products.

Hot water systems

To prevent scale build-up in your hot water system you should release the pressure valves for a few seconds each month.


Put a slice of lemon in the kettle, fill with water and bring to the boil, then refill before next use.