Manganese (Mn++)
Ammonium (NH4+)
Nitrite (NO2-)
Aggressive carbon dioxide (CO2)
Phosphorus (P)
Arsenic (As+++)
Hydrogen sulphide (H2S)
Methane (CH4)
In the European countries the EC directive on drinking water must be followed. In general, the selection of treatment method is greatly related to the water source available and to the standards set out by the local authorities.