Much of the discussion revolves around sodium. Water softening via the ion exchange principle introduces a small amount of sodium into the water - in short, every calcium or magnesium ion is replaced by a sodium ion.
It helps to distinguish between sodium and table salt. Table salt comprises sodium and chloride, sodium being 40% of that.
In itself, sodium is not considered a risk. We all need sodium in our diet, because it is critical to the overall function of every cell in our body. However, many governments advise that too much sodium drives up blood pressure which can lead to an unhealthy heart. Therefore, many water quality regulations set a 200 ppm (or 200 mg/litre) maximum for sodium content in drinking water.
What does this mean for me?
Whether the softened water in your home is safe to drink, depends on the hardness of your water. If your water is very hard, a large amount of calcium and magnesium will be replaced by sodium, which could get your total sodium level over the maximum set by regulation.
A water softener will add 46 mg/litre of sodium for every 100 mg/litre of calcium carbonate (hardness minerals) taken out of the water. So, for example, if you have a hardness of 200 mg/litre (or 200 ppm), a softener will add 92 mg of sodium to every litre of water.
To put this into perspective: 400 mg of sodium equates to a pinch of salt. On average, we consume each day 3240 mg of sodium or 8.1 grams of salt - over a teaspoon.
Therefore, once the water hardness in your home exceeds 400 mg/litre of calcium carbonate, your water softener will push the sodium level in your water over the treshold, so a separate drinking tap with unsoftened water will be advised. This will occur in a few areas that have extremely hard water. You can get this information by going to your local water company’s website.
So can I drink softened water?
Yes. Where the water hardness is below 400ppm calcium carbonate, softened water complies with practically all drinking water regulations. There are two specific situations where the use and drinking of softened water is inadvisable. These are:
- In the reconstitution of infant formula powders, as softened water could affect its fine nutritional balance, or;
- For anyone on a medically prescribed low sodium diet.
What if my water hardness exceeds 400 ppm?
Installing a hard water tap obviously isn't the end of the world, but ... you will get the downsides of hard water with said tap. A second option could be to install a reverse osmosis drinking water filter, which will remove the majority of the minerals, therefore greatly reducing the sodium content in softened water.
An EcoWater professional can advise you on the installation of a water softener, and whether a hard water tap is necessary in your home.