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  • Writer's pictureGary Moller

Which Geothermal Hot Pools are Safe to Bathe in?

Updated: Mar 27

"Kia ora Gary, can you please email me a map of the safer thermal pools to attend?

Interested if Morere is OK.

I haven't gone to any hot pools due to your comments in 2020."

As background, I would guess I now have as many as 1,000 cases of elevated arsenic levels due to bathing in geothermal hot pools with this naturally-occurring toxic metal in the water. In some cases, people's health has been adversely affected, many long-term. I'm incredibly frustrated and disappointed that there has been no action about this health hazard despite overwhelming evidence of harm to the public. They could have done so much to introduce remedies while domestic and international tourism halted during the Pandemic Lockdowns, but now these opportunities are lost.

The harm is real: Please read this article before proceeding:

The most obvious measure to ensure public safety is to test all of New Zealand's geothermal bathing facilities for the presence of toxins such as arsenic and cadmium, then do the following:

  1. Close any facilities or pools within these facilities with toxins that exceed the World Health Organisation's maximum safe levels for drinking water.

  2. For those under the maximum, the facility must display the test results, as they do for biological contaminants.

  3. In cases where levels exceed safe limits, these can be made safe by converting to heat exchange warming of municipal water.

Where is arsenic found in geothermal water in NZ?

"The toxic element arsenic is widespread in New Zealand's aquatic and terrestrial environments. Elevated concentrations of arsenic in ecosystems result from both geogenic and anthropogenic sources. Arsenic is ubiquitous in all of the geothermal areas and waterways that fall within or pass-through the Taupo Volcanic Zone (TVZ), an area in the central North Island that stretches from Mt Ruapehu to White Island (Figure 1). On its way to the surface, super-heated geothermal water dissolves appreciable amounts of arsenic from the surrounding volcanic rock. Aggett and Aspell (1978) have reported that in some lakes and rivers of the TVZ, arsenic concentrations often exceed 0.01 mg/L, the recommended maximum concentration for arsenic in drinking water set by the World Health Organisation (WHO) and the New Zealand Drinking Water Standard (NZDWS). The arsenic loading in surface waters is exacerbated by the commercial exploitation of geothermal power (Axtmann 1975).

Red box contains the volcanic "arsenic belt".

Arsenic levels in New Zealand's longest river, the Waikato, seldom fall below the New Zealand drinking water standard of 0.01 mg/L (Robinson et al. 1995)."

My Recommendations before bathing in geothermal hot pools

  1. Be very cautious about bathing in any geothermal water within the "arsenic belt" of the Central North Island.

  2. Before bathing in a commercially operated pool, ask to see their water testing results for arsenic and other toxins: Do not take their word for it that the water is safe to bathe in - ask for the evidence.

  3. While geothermal waters outside the arsenic belt may be safe, ask to see the water testing results before bathing.

  4. Municipal water warmed by heat exchange is safe for bathing.

Further Reading

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