Contaminants will include pathogens, organic chemicals, inorganic chemicals and suspended solids. Biological pathogens may include fungi, cysts such as Giardia and Cryptosporidium, bacteria and viruses. Naturally occurring organic chemicals are predominantly tannins from vegetation in gutters. Synthetic organics such as pesticides may be from agricultural and industrial activities. Inorganic chemicals can be naturally occuring mineral salts and synthetic salts such as fertilizers from human activities. Suspended soilids may be very high after heavy rain.
Treatment solutions may include coarse filtration, sub micron filtration, organic reduction, inorganic reduction and disinfection.
Typically applied technologies include:
Coarse filtration - backwashing multimedia filter and bag filter or cartridge filter
Sub micron filtration - self cleaning ultrafilter
Organic reduction - activated carbon, anion resin
Inorganic reduction - reverse osmosis
Disinfection – chlorine, ozone, ultraviolet irradiation