Any water supply which is not a Town mains which meets drinking water standards should be considered a possible source of microbiological contamination. These can include bacteria like E.coli, Salmonella and Campylobacter. Viruses like Hepatitis A & E, Norovirus and Calcivirus. As well as Protozoan parasites like Giardia. As these are living organisms, they are likely to be present intermittently and the number of them present will vary. These are commonly found in rain water supplies, a surface waters, springs and shallow or unsecured bores. This can also be a concern with some water schemes, particularly irrigation schemes that some people have connected to their homes.

Chemically rain water is very good, however as it falls through the air, it dissolves in some Carbon Dioxide, which makes it slightly acidic and corrosive to metal plumbing. This is more noticeable in plastic tanks, concrete tanks can offer some protection as they raise pH slightly.

Bore/Well/Spring Water
There are not many people on these supplies around Northland, but those which are present often have undesirable levels of iron, manganese, hardness, Silica and low pH. Those near the coast can have additional issues with salty water intrusion.

Surface Water (Streams, Rivers, Creeks Dams etc)
Surface water is a common water source in Northland. These tend to have heavy levels of sediment in them after rains and they can become discoloured from dissolved organic matter. Depending on the land they flow through, some can also have other mineral issues, like hardness and iron.

Water Schemes
There are a number of water schemes in Northland, which people can use in homes at their own risk. These often have little or no treatment and the householder is responsible for making sure it is safe to drink. These often have issues with sediment, discolouration. Other issues can include low pH and hardness.