Water softeners are systems that are installed at the entrances of houses and extract calcium and magnesium from water for preventing limescale.

The system operates based on an ion exchange resin, replacing calcium and magnesium ions with sodium ions, sodium being found in cooking salt.

The water produced is rich in sodium and bacteria, and causes a loss of 20% of the calcium and 80% of the magnesium required in the body and damage and salinate aquifers. 

There is great concern of dissolution and loss of undrinkable substances from pipes, solar panels, boilers and even taps into drinking water and enrichment of water with bacteria; raising the sodium level in water may cause damage to the vascular system, blood pressure and the heart.

A well known phenomenon is that of "red water" where water takes a rusty hue, which attests to piping dissolution.

The resulting water is excellent for showering and cleaning but is not considered potable.