For drinking water, use EDR ...

For drinking water, use EDR plus pre-treatment and disinfection on the final stage (ex-chlorine or ozone gas). For Cooling System EDR plus post treatment to reduced silica and metal conditioner when circulating. RO could be applicable on both application but the low recovery on reject/concentrate is too much and the fact that high silica would clogged the RO membrane ( there is a solution on high reject by using high efficiency RO membranes and to address silica, very expensive de-ionization process on top of expensive membranes at post & pre-treatment). Hope this will help.