Water Softeners and Conditioners

Water softeners and conditioners are often used in areas where the mains water supply is hard. In the UK, this roughly equates with the eastern half of England where groundwater constitutes a large proportion of public supply. Water efficient fittings often rely on small flow apertures and are prone to scaling. As such, water softeners and conditioners may become a more common inclusion in homes specified to high water efficient standards in hard water areas. A second driver is that manufacturers of combination boilers often recommend some form of scale management, such as softened water, for their product to prolong its lifetime and maintain its efficiency.

Water softeners work by exchanging calcium ions in the water for sodium ions. The advantages of softening hard water include minimising scale and thereby maximising efficiency and lifespan of various fittings including boilers. The disadvantages of using a water softener include cost outlay, salt consumption, need for maintenance, energy consumption and the increased consumption of water during normal operation.

The Water Calculator will only include the water consumption from the regeneration cycle if the consumption is above the 4% benchmark of good practice. This 4% benchmark is derived from the total volume of water treated between regenerations, divided by the amount of water needed to carry out the regeneration cycle. This volume will be dependant on the hardness of water supplied to the development and needs to reflect this when used in the Water Calculator.

When including a water softener, developers must ensure that water supplied for potable uses meets the water quality standards particularly in terms of sodium content. This is most often interpreted as a regulatory requirement for a supply of drinking water in the kitchen that has not been softened. We recommend that where a water softener is to be installed, the supply of water to the kitchen tap is from the mains and not softened.

Inclusion of a water softener in the specification for a dwelling requires an addition calculation under the Water Calculator (Figure 8).

Figure 8. Code for Sustainable Homes calculation for water softeners that consume more than 4% of total capacity.

This calculation only comes into play if the softener consumes more that 4% of its total capacity. Whether it does so or not will depend in part on how heavy the water is.

At the present time, there is no requirement for softeners to be labelled with water consumption rates. The information required can generally be obtained from the manufacturer or through the UK Water Trade Association (UKWTA) . The UKWTA have expressed an intention to provide a listing on their website of softeners that consume less than 4%.

As distinct from water softeners, water conditioners use magnetism or electrolytic action to temporarily disrupt Ca and CO3 ions in water supply. They do not consume water but electro-magnetic conditioners do require a power supply. As ionic disruption is temporary, conditioners slow, but do not necessarily prevent, build-up of scale in small exposed apertures of low flow fittings.