Some higher levels of naturally-occurring arsenic in self-supply drinking water

Members of the public who draw groundwater from private bores need to know these bores may contain some higher levels of naturally-occurring arsenic, and fail the national drinking-water standard.

Hawke’s Bay Regional Council has recently confirmed some higher levels of arsenic in groundwater at three Hawke’s Bay locations. Concentrations of arsenic at these three locations have been greater than the maximum acceptable value of 0.01 milligrams per litre (mg/L) of (potable) water, as per Drinking Water Standards for New Zealand 2005 - DWSNZ (revised 2008).

Water is considered safe to drink if it meets levels set out in the DWSNZ. Self-suppliers are responsible to maintain, monitor and treat their own water.

“Long term consumption of water with arsenic concentrations greater than 0.01 mg/L can cause adverse health effects, even increasing the risk of cancer,” says Principal Groundwater Scientist Janine Barber.

Elevated arsenic levels occur naturally in groundwater, due to the presence of specific materials in the aquifer. The release of arsenic from surrounding materials is local to specific bores and does not occur consistently throughout aquifer systems.

“This is not unique to Hawke’s Bay, and occurs in other sediment-dominated groundwater systems around NZ, such as in Waikato, Manawatu, Marlborough, Canterbury, and worldwide,” adds Ms Barber.

“Unless specifically testing for levels of arsenic, anyone who has recently tested their self-supply water quality will not know whether high levels of arsenic are present,” says Ms Barber.

The Regional Council advises self-supply bore owners to sample and test their water for elevated levels of arsenic.
Information on water sampling is available from laboratories who can perform analysis, including Hill Laboratories - Hamilton 0508 44 555 22; Analytical Research Laboratories - Napier 06 835 9222 and Water Testing Hawke’s Bay - Hastings 06 870 6449.

People wanting health advice or who have specific health concerns should talk to their GP. For information on what test results might mean in terms of risk to health, call the on-call Health Protection Officer on 06 878 8109.

The Regional Council works closely with Napier and Hastings Councils and the Hawke’s Bay District Health Board in matters concerning the environment and public health.

Find out more:

hbrc.govt.nz, search: #arsenic

health.govt.nz/your-health/healthy-living/environmental-health/hazardous-substances/arsenic-and-health

HBRC self-supply drinking water - presentation from May 2018

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