Consequently , there are very few rivers from which the water is safe to drink without some form of sterilisation or disinfection .
Upland waters draining areas frequented by sheep , goats or deer may also harbour a variety of opportunistic human parasites such as liver fluke .
There are very few rivers from which the water is safe to drink without some form of sterilisation or disinfection .
Upland waters draining areas frequented by sheep , goats or deer may also harbour a variety of opportunistic human parasites such as liver fluke .