We’ve all heard of hard and soft water. Yet, we never seem to consider the difference between them. Many of us know that in the UK they are divided by location but what is it that earns them separate names?
Well, let's start with soft water since all drinking water typically starts off as being “soft”. Quite simply it can be defined as water that doesn’t contain readable levels of minerals. Instead, the only ion it contains is sodium. By this definition, it’s quite easy to work out that hard water is the opposite. Unlike soft water, it contains high levels of minerals, such as magnesium, calcium and carbonates, which cause it to leave a limescale residue.
How Does Water Become Hard?
All the water we drink starts off as rain. It is classified as soft water since it doesn’t contain any minerals or additional chemicals. However, this changes when it hits the ground. Depending on the geography of the landscape, the ground may be permeable to the rain. Therefore, the rain can pass through porous rocks such as limestone and attract ions to it as it moves. These ions are the minerals we mentioned before, such as magnesium and calcium.
Water is able to attract these ions since it has a negative OH- charge, which counters the positive +2 charge of various minerals found in the rocks. As a result, water passing through porous rocks can loosely bond with many positive minerals. This causes the water to become “hard”.
The Geographic Divide
It is common knowledge that soft water is typically exclusive to northern England, with the large exception of Cornwall. What causes these areas, in particular, to have soft water though? To answer that we must backtrack to the formation of drinking water from rain. The key difference between hard and soft water areas is the permeability of the ground. Areas of hard water are made up of porous rocks such as limestone. These rocks allow water to pass through them and travel underground, eventually forming in aquifers and rivers. That water is then collected and circulated by water companies.
Soft water areas are unsurprisingly not permeable to water and they are made up of large amounts of non-porous rock, such as granite. These rocks don’t allow water to travel through them, so it instead it runs on top of them until it meets with a river or stream. As a result, the water hasn’t had contact with areas of high mineral concentration, so it remains soft.
Water Alternatives
There are advantages and disadvantages to hard and soft water types. Of course, soft water has the advantage of not causing limescale. However, some people prefer being able to consume minerals from their water.