This article looks at the potential health effects of drinking softened water. It explains how water softeners work, where they are used and considers some of the potential health concerns, highlighting a number of specific circumstances where softened water should be avoided. It concludes with some practical advice for those in hard water areas.
Why use a water softener?
Many of us who live in hard water areas will run our drinking water through some sort of softening equipment before using it in the home or at work… and there are a range of excellent reasons for doing this.
Hard water, that’s water that contains higher levels of calcium and magnesium salts can cause damage caused by the build-up of limescale deposits over time inside kettles, washing machines, dishwashers, central heating boilers and industrial equipment.
Some people also find that they prefer the taste of water which has been softened.
There are however some concerns about whether softened water is safe to drink, stemming from the chemical processes which are used to soften the hard water supply.
What are the health concerns of drinking softened water?
Most of the concerns about the potential health problems from drinking softened water revolve around the impact of sodium salts and their effect on our health.
This is because most hard water is softened using a process called ion exchange.
In very simple terms, this ion exchange is a chemical process which involves taking the “hard” minerals of calcium or magnesium out of hard water, and replacing them with sodium to make the water softer.
When people hear references to sodium, they immediately think table salt – however, the two aren’t quite the same thing.
Sodium chloride is the chemical name for common table salt.
The sodium makes up around 40% of the volume of the compound… so sodium on its own isn’t a risk.
Sodium is an essential nutrient for the human body, and helps the cells function in the correct way.
Too much sodium is a problem however, as high levels can lead to increased blood pressure, and the related risks of heart disease or stroke.
In the UK the Water Supply (Water Quality) Regulations set out acceptable levels of sodium in drinking water… they are currently set at a maximum of 200 parts per million, equivalent to 200 milligrams of sodium per litre of water.
Should water softeners users be worried about drinking softened water?
Don’t automatically assume that the water which comes out of the filtration or water softener system you use in your home isn’t safe to drink.
Understanding whether it’s safe to drink will depend in a large part on how hard your water is to start with.
In locations with very hard water, there are more calcium and magnesium ions to remove and replace with sodium, and this could in some cases push the sodium content of your drinking water over that 200 parts per million set out in the UK water quality regulations.
Water softeners add approximately 46 milligrams of sodium for every 100 milligrams of calcium carbonate which they remove per litre of water.
For example, if your starting point is water which has 200 milligrams per litre of calcium carbonate, then after it goes through the softening process you will have water which has 92 milligrams of sodium per litre of water.
Government research has shown that the average adult in the UK consumes around 3200 milligrams of sodium every day, equivalent to just over 8 grams of salt.
So, if your incoming water supply is made up of very hard water, it is therefore wise to keep a separate tap for drinking water so that you’re not consuming too much process softened water which could push your daily intake of sodium over recommended safe levels.
This is primarily an issue in the east of England, where the hardness of the water is affected by the underlying geology making.
There should be information on the website of the company which supplies your water about whether your water supply is particularly hard.
Should you be drinking softened water at all?
If the water hardness in your area is below 400 parts per million calcium carbonate, then when it is softened your tap water should be considered safe to drink… this should apply to most households in the UK.
There are however two situations when the general advice is against using water which has been passed through a water softener and these are:
Water softening advice if you live in a hard water area
Having a separate “hard water” tap purely for drinking water is the most straightforward way of dealing with the problem of increased sodium in softened water.
A second – and more costly – option is to look at other methods of softening filtered water, such as using a reverse osmosis filter.
Costs of reverse osmosis membrane technologies are reducing all the time, and should become even more affordable in the future.
If you do want to have softened water for drinking in a hard water area, seek advice from an industry expert on your individual circumstances.
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