Water supplied to domestic properties may be further treated before use, often using an in-line
treatment process. Such treatments can include water softening or ion exchange. Many systems
also claim to remove residual disinfectants and heavy metal ions.
Saline water can be treated to yield fresh water. Two main processes are used, reverse osmosis
or distillation. Both methods require high energy inputs and are usually only used where fresh
water is difficult to source.