Hard Water Treatment

Indoor water tap

Water hardness is a natural characteristic of much of Ireland's drinking water supply given the geological characteristics of our landscape. Hard water contains high levels of natural minerals absorbed from rock and soil.

Formation of hard water

Rain water is classified as ‘soft water’ and normally contains very low concentrations of minerals. When rain falls, it soaks into the surface and comes in contact with soil and rock. If minerals such as calcium and magnesium are present in the soil and rock they absorb into the water. This then becomes hard water.

Water hardness levels vary across Ireland, depending on soil and rock types. Hard water is often present in rivers and lakes used to source our drinking water.

Due to its higher mineral content, hard water typically tastes better than soft water. However when hard water is heated it forms a white calcium deposit known as lime scale, which can result in a build up of limescale on the inside of electrical appliances or as a visible layer on the surface of a hot drink (e.g. tea). Hard water has no odour however.

There are several reasons why chemicals are not used to soften hard water, specifically:

  • There are no health risks involved in drinking and using hard water. Conversely, hard water may actually offer health benefits above that of soft water because of the higher mineral content of hard water (such as Calcium and Magnesium)

  • Softening water removes beneficial minerals from hard water

  • There are no legislative requirements to remove hardness from drinking water

  • Depending on the technology used, artificially softened water may not be suitable for everyone to drink, e.g. increasing Sodium levels caused by salt softening may not be suitable for infants or at-risk groups

  • Hard water can create an internal protective coating on lead pipes or fittings. This can prevent metals such as lead leaching into drinking water supplies

Treating and Preventing Limescale

Limescale is formed when you heat hard water. It can form a film or fur within kitchen appliances and heating systems. It may also reduce the effectiveness of washing detergents and/or soap.

To treat and prevent limescale build up in hot water appliances and systems, a number of steps can be taken. However, remember to always follow the manufacturer’s instructions for any of your appliances that use water.

  • Kettles or other drinking water boilers
    • Place a stainless steel wire scale collector in your kettle.

    • Rinse plastic kettles regularly if a build-up of limescale develops on the water surface.

    • Do not leave leftover boiled water sitting in the kettle.

    • Regularly descale your kettle – consult your local hardware store for advice.

  • Hot water heating systems
    • Heating systems that recirculate the same water within a closed loop are normally not affected by limescale formation. However if you have a heating system where fresh water can replace any water lost from the system, limescale may develop over time and reduce the efficiency of your heating system. This may become evident through your heating pipes starting to rattle or your radiators taking longer than normal to heat. If you are concerned you should consult a plumber to examine your heating system.

    • Reducing the temperature set point of your water heater may reduce the level of limescale formation.

  • Washing Machines, Dishwashers and Hard Water
    • Dishwashers often have built-in water softeners. These should be used according to the manufacturer’s instructions.

    • You can use water-softening products in your washing machine to help prevent limescale build-up.

Install a Softening Unit

If hard water is a problem in your home you can install a domestic softening unit. It is best to talk to your local plumber for advice in this area (Irish Water, 2018).

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