Water

Rainwater that percolates down major faults and fractures, and is retained in suitably porous and permeable rocks, can be heated by molten rocks at great depths in the crust. Rather dilute brines are formed as a result of fluids and gases from the molten rocks being mixed with the rainwater, and also because of reactions that occur between the water and the rocks at high temperatures and pressures. READ MORE...

Auckland's water (like water throughout New Zealand) is a combination of water from dams and water from underground springs. Depending on the source of the water, it has different contaminants: metallic ions, organic compounds and biological materials. To make this water safe to drink, most of these have to be removed. Fluoride is also commonly added to the water during the treatment process as fluoride strengthens teeth. READ MORE...

Sewage is a mixture of domestic and industrial wastes. It is more than 99% water, but the remainder contains some ions, suspended solids and harmful bacteria that must be removed before the water is released into the sea.

The treatment of wastewater is divided into three phases: pretreatment, primary treatment and secondary treatment. READ MORE...

Ion exchange resins are polymers that are capable of exchanging particular ions within the polymer with ions in a solution that is passed through them. This ability is also seen in various natural systems such as soils and living cells. The synthetic resins are used primarily for purifying water, but also for various other applications including separating out some elements. READ MORE...