Put very simply, a water softener works by passing hard water through a cylinder containing ion exchange resin.

The resin consists of tiny beads that attract and retain the hardness minerals, letting the now softened water flow on.

Periodically, these resin beads are automatically cleaned and regenerated by rinsing with a small amount of brine - a salt solution.

The brine, with the accumulated hardness, is then flushed away to drain.

All this takes place automatically within the water softening appliance, there is little else to do other than the occasional top-up with salt.