Health Effects of Drinking Softened Water

Despite concerns about sodium and hardness levels in drinking water that have been raised spasmodically over the last forty years, the World Health Organisation advises that the decision whether or not to drink softened water should be limited only by whether or not you like the taste. WHO’s current, official position, published in the Guidelines for Drinking-water Quality 2006, is that no firm conclusions can be drawn on any possible health effects of sodium in drinking water.

The vast majority of softened water in the UK is safe to drink over the long term. Its suitability for drinking is measured by the levels of sodium in the water. To comply with the UK’s Drinking Water Regulation requirement for safe drinking water, sodium levels should not exceed 200 mg/l.

This policy is far from universal, though. In most of the European Union Member States, the national regulations lists sodium only as an indicator parameter, which does not contribute to the definition of whether water is fit to drink. In the USA there is no limit on sodium in the National Primary or Secondary Drinking Water Regulations.

  Softeners work by replacing the hardness minerals with sodium. So, the more hard minerals in the water supply, the higher the levels of sodium in the softened water. For most areas of the UK, the sodium levels of softened water will be well within this limit. However, in a few parts of the UK where the drinking water is particularly hard, sodium levels may exceed 220 mg/l.