Is Softened Water Safe to Drink? Sodium in Softened Water Explained
Softened water contains elevated sodium. For most adults this is not a concern, but there are guidelines for infants and people on sodium-restricted diets. Here is what you need to know.
How Sodium Gets into Softened Water
A salt-based ion exchange water softener removes calcium and magnesium ions from the water by exchanging them for sodium ions. For every calcium or magnesium ion removed, two sodium ions are added to the water. The net effect is that softened water has a higher sodium content than the original hard water supply.
The amount of additional sodium depends on the original hardness of the water. In London, where water hardness is typically 300 to 380mg/l as calcium carbonate, a correctly calibrated softener adds approximately 200 to 250mg of sodium per litre of softened water. For comparison, the European Union drinking water standard for sodium is 200mg/l, and the UK Drinking Water Inspectorate recommends that sodium in drinking water should not exceed 200mg/l for infants and those on sodium-restricted medical diets.
It is important to note that 200 to 250mg/l of sodium in a glass of water is substantially less sodium than is found in a slice of bread (approximately 150 to 200mg per slice), a serving of cereal (100 to 300mg per serving), or any typical portion of cooked food. For most healthy adults, the additional sodium contributed by drinking softened water in moderate quantities is nutritionally insignificant.
Who Should Not Drink Softened Water
The UK Water Treatment Association, the British Water Quality Group, and NHS guidance all recommend that softened water should not be used as the primary source of drinking water for the following groups:
Infants: Baby formula should always be made with unsoftened water. The kidneys of young infants are not yet fully developed and may be less able to process elevated sodium levels. NHS guidance states that water used to make up powdered infant formula should not be softened.
People on sodium-restricted diets: Individuals advised by their doctor to restrict sodium intake — for example, those with hypertension, kidney disease, or congestive heart failure — should use unsoftened water for drinking and cooking. The additional sodium from softened water may be a meaningful contribution to daily intake for someone on a strict low-sodium regimen.
Pregnant women: NHS guidance on sodium intake during pregnancy recommends moderation, and some guidance from water softener manufacturers suggests using an unsoftened supply for drinking during pregnancy as a precautionary measure.
For Everyone Else: Not a Concern
For healthy adults and children who are not on sodium-restricted diets and who are not infants, drinking softened water in normal quantities is not associated with any health risk. The additional sodium from softened water is a modest contributor to daily sodium intake, easily offset by any reduction in processed food consumption. The UK Department of Health recommends no more than 6g of salt (2.4g sodium) per day for adults. A litre of softened London water contributes approximately 0.25g of sodium — around 10 percent of the daily recommended maximum if that were the only sodium source, which it never is.
The Dedicated Drinking Water Tap: the Standard Solution
Because the guidance recommends avoiding softened water for infants and those on sodium-restricted diets, and because many people simply prefer the taste of hard water for drinking and cooking, the standard practice when installing a water softener is to fit a separate bypass tap at the kitchen sink fed directly from the unsoftened mains supply. This provides an unsoftened cold water supply for drinking, cooking, and making drinks at the kitchen sink, while all other outlets in the property — the hot water taps, the shower, the bathroom basin, the washing machine and dishwasher — are fed from the softened supply.
Prestige Engineers includes the dedicated unsoftened drinking water tap as standard in every water softener installation across London. The tap is typically installed alongside the existing kitchen cold tap and clearly identified. No additional plumbing disruption beyond the softener installation is required. Contact us for a water softener supply and installation quote across all London boroughs.