Health Effects of Drinking Softened Water
Drinking Softened Water Questions
Yes, but how much salt is that? Yes, but how much salt is that?
At a typical calcium carbonate hardness of 300 mg/l, such as Greater London, the sodium in the water as a result of softening would increase by 138 mg/l. Therefore each litre of drinking water would contain an additional 138 milligrams of sodium over and above that which was in the water to start with.
However, this is the sodium content – not the salt (sodium chloride) content; to equate it to salt, the chloride must be added. 138 mg/l of sodium is equivalent to 348 mg/l of sodium chloride. Therefore, the equivalent increase in salt intake by the average individual drinking two litres of softened water a day is 0.696 g. This is about one tenth of a teaspoonful.
The Food Standards Agency(5) has published data on the dietary intake of salt and the average salt content of typical foods. The average total daily salt intake is about 9,500 milligrams for an adult, so the contribution from softened water would be about 7% in a typical hard water area, assuming a 2 litre daily consumption. By comparison, white bread contributes 10.2% to the average daily salt intake, bacon and ham = 8%, and breakfast cereals = 4.9%. So to say you shouldn’t drink softened water is the same, in these terms, as saying you shouldn’t eat bacon, a bag of crisps or eat white bread!
5 McCance & Widdowson on behalf of the Food Standards Agency