Hard water

Hardness is a natural characteristic of much of Ireland's drinking water supply. Hard water contains high levels of natural minerals absorbed from rock and soil.

Hard water is not harmful to your health. In fact, the higher mineral content may offer health benefits above that of soft water.

Taste, appearance and smell

Due to the higher mineral content, hard water typically tastes nicer than soft water. Hard water looks the same as soft water, however when heated, it forms a white calcium deposit known as limescale. You may notice a build up of limescale on the inside of your kettle or as a visible coating on the surface of a hot drink (e.g. tea). Hard water has no smell.

Find out what could be causing your water to have an unusual taste or smell.

How hard water is formed

Rain water is soft water which normally contains very low levels of minerals. When rain falls, it seeps into the ground and comes into contact with soil and rock. If minerals like calcium and magnesium are in the soil and rock they absorb into the water. It then becomes hard water.

Water hardness levels vary across regions in Ireland, depending on the soil and rock types. Hard water is often present in the rivers and lakes we use to source our drinking water. When we abstract and treat this water to make it safe to drink we do not remove the minerals, as they pose no health risks.

Why we don't soften hard water

There are good reasons why we don't chemically soften hard water.

  • There are no health risks involved in drinking and using hard water
  • Softening water removes beneficial minerals from hard water
  • There is no legislative requirement to remove hardness from drinking water

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

Hard water can create an internal protective film on lead pipes or fittings. This can prevent metals such as lead leaching into your drinking water supply.

Treat and prevent limescale

Limescale is formed when you heat hard water. It can form a coating inside your kitchen appliances and heating system. It may also reduce the effectiveness of detergents and soap.

These tips help to treat and prevent limescale build up in your hot water appliances and systems. 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 there is limescale floating 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 generally not affected by limescale formation. If your heating system replaces any water lost from the system with fresh water, limescale may build up over time. This can reduce the efficiency of your heating system causing your heating pipes to rattle or your radiators to take longer than usual to heat. If you are concerned you should consult a plumber.

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

Washing machines and dishwashers

Dishwashers often have built-in water softeners. These should be used according to the manufacturer’s instructions. You can also use water-softening products in your washing machine to help prevent limescale build-up.

Install a softening unit

If you find hard water is a problem in your home you can install a domestic softening unit. Talk to your local plumber for advice. Irish Water cannot recommend any particular units or guarantee their effectiveness.

For more information visit the World Health Organisation (WHO) website.