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Our Water Story

173 years in the making…

Our water story: the journey from rain to thermal water

For decades people from all over the world have flocked to Hanmer Springs to relax and enjoy our thermal pools. 

But did you know that the water you’ve been enjoying for all those years is actually 173 years old? 

The water in our thermal pools starts as snow and rain falling on the Hanmer Springs mountains. It seeps into the Greywacke basement rock and comes to rest in a reservoir some two kilometres underground, where it is warmed by heat radiating from the earth’s core. Today, we draw the water to the surface and use it for bathing and heating purposes.

In addition, we’ve been working hard to improve the quality of our facilities to ensure they’re truly world class.

That includes the recent redesign of our main changing rooms (now featuring luxurious underfloor heating!) 

So sit back, relax, and enjoy what nature created all those years ago!

Water Story

What's in our water?

Full of the good stuff!

Everything else there is to know about our water

Heat radiating from the Earth’s core raises the temperature of the rainwater in the underground reservoir. This heated water then rises to the surface through a series of interconnecting fractures in the greywacke rock.

  • Where does our water come from?

    When the springs were first discovered, the hot water rose to the surface under artesian pressure. Today, the natural upflow of heated water has diminished, and the water is pumped from a bore that was drilled into a fractured part of the rock in 1975 (original drilling was in 1911).

    The thermal water is drawn at a rate ranging from 4 litres per second to a maximum of 8 litres per second. It was originally drawn from a depth of 10 metres, but is currently drawn from approximately 70 metres. Seasonal differences mean this fluctuates throughout the year, and we work to minimise water loss throughout the year. 

  • What temperature is the water?

    The water comes out of the bore at a temperature of 52°C, having lost some of its heat through convection on the way to the Earth’s surface. Heat is then extracted out of the water using a series of heat exchanges until it reaches bathing temperature of between 32-42°C.

  • Is the water treated?

    Without some form of human intervention, water from the bore would be unpleasant to bathe in. So yes, the water is treated, but only very minimally. The water first passes through a series of gauze strainers which remove large pieces of debris such as leaves and twigs. It then passes through an exceptionally fine filter, to remove any smaller impurities.

    That's it for our sulphur pools - they receive no additional treatment.

    For our thermal pools, the water is tested for acidity and water purity; the former being controlled by the addition of carbon dioxide gas. Other measures to maintain high quality include the addition of chlorine at the ratio of 2.5 parts per million, and recirculating the water every 3-4 hours.

  • What is the chemical make-up of the water?

    The geothermal water is described as a NaCI (sodium chloride) water. An average analysis shows about 380 mg/l Na, 480 mg/l Cl and 190 mg/l bicarbonate. Minor amounts of Boron, Calcium and Carbonate are also present, together with other elements. See What's In Our Water? above to learn more.

  • What is the therapeutic value of the hot pools?

    Communal bathing in hot water for relaxation and therapeutic reasons dates back to Roman times. Today, hot pools are becoming increasingly popular to relax and ‘unwind’ in and are used extensively to treat rheumatic conditions and paraplegia. They are also popular for treating orthopaedic conditions such as bone fractures and soft tissue injuries.

  • Who owns the pools?

    Formerly part of the Queen Mary Hospital, the pools are on government reserve land, but are owned by the Hurunui District Council. The pools are controlled by an experienced management team, which reports to a committee. Profits not reinvested into the operation are returned to the Hurunui District Council and invested in the physical reserves of the wider Hurunui District.

  • Is there a health risk?

    Maintaining the highest standards of water quality is our number one priority and is done by testing the water in our own laboratory three times daily. Testing is also carried out to determine the presence of the amoeba bug which can cause amoebic meningitis. This is despite the fact that the bug is unlikely to exist in the water given the way it is treated. An independent scientific laboratory in Christchurch also undertakes regular water checks. In their 125 year history, the hot pools have never had an incidence of the amoeba bug, but as an added precaution bathers are advised not to put their heads under the water.

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