New Zealand bore and roof water supplies are naturally acidic, some as low as 4.5 pH. Most are around 6.0 – 6.8 pH. At these pH levels, the water is a natural solvent and will try to correct itself by absorbing minerals/metals from pipes, taps and tanks.
A lot of the minerals/metals contained in the water are toxic to humans in larger doses (i.e. lead, zinc, copper and others).
FILTEC has two solutions for pH neutralisation but if iron and manganese concentrations are high in your water test, use a Calcite Filter.