Radiological contaminants are contaminants that are radioactive. In New Zealand, only natural sources of radioactivity need to be considered. The DWSNZ provide MAVs for two general types of radiation, irrespective of their source: alpha particles and beta particles; and an MAV for a specific radioactive contaminant: the gas radon. Radon is a concern in groundwaters because they are in close contact with rock and soil, which are the source of the gas. Use of water containing radon will increase the concentration of gas in buildings and therefore the amount inhaled.
The DWSNZ 2005 require new groundwater sources to be tested for radiological contaminants and groundwater sources in general are required to be tested every 10 years.26
26 This is a new requirement introduced in the 2005 edition of the DWSNZ.