Well-water not up to standard

Fresh and bubbly mountain water, right from the rocky depths. But it is not at all certain that this water is fit for human consumption. Photo: Terje Mortensen

Sixty per cent of wells that get their water from crystaline rock, produce water with excessive amounts of -substances that may be damaging to our health.

By Tore Oksholen

Six out of ten wells in Norway that are fed by water from crystaline rock, produce water with excessive quantities of one or more element. This is confirmed by a comprehensive investigation involving Bjørn Frengstad from the Department of Geology and Mineral Resources Engineering at NTNU. The study was done jointly by Norwegian Geological Research and the Norwegian Radiation Protection Authority, and investigated 1 604 rock-drilled wells from all over the country.

Radon, fluorine, sodium, uranium ...
The research found that water from three out of ten wells had concentrations of pH, radon, fluorine and/or sodium that exceeded what is permitted. Radon is thought to be a factor that increases the danger of cancer, whereas too much fluorine can damage to developing teeth. People with high blood pressure should avoid ingesting too much sodium. Furthermore, water from three out of ten wells contained too much iron and/or manganese. However, this is more a matter of convenience and appearance.
The investigation also confirms that almost two out of ten wells produce water with a content of natural uranium which is above the highest allowable concentration in the USA. The Norwegian authorities have not yet decided on the standard levels for purification. Also opinion varies about how dangerous natural uranium really is.

Difficult to predict
What we are talking about is natural pollution which is released from rock by the action of groundwater. It is actually impossible to predict how much there is of each chemical substance in well-water until the well has been drilled. This research enables us to predict something about the likelihood that a well in a specific type of rock will provide sub-standard water.
The same rock may contain water which has all sorts of different concentrations of the relevant substances. This is because factors such as fractures, the extent of erosion and the length of time that the groundwater has been in the rock, also impact on the amount of the substances that percolate into the well. Metals such as copper and lead have a solubility which is dependent on the acidity of the water – its pH. The more acidity in the water, the easier it is for the metals to dissolve. The level of acidity is also a factor which varies considerably, but most of the wells supply water with high pH in which heavy metals have low solubility.

Different cleansing techniques
There are various methods of water cleansing and these depend on the substances that are to be removed. Radon is a form of gas which is removed by airing the water in separate tanks before it is piped to domestic users. Different filters can be used to get rid of fluorine and metals. Because chemical properties vary from element to element, the cleansing method must be adapted to the chemistry of the water in question. The price-tag for water-cleansing equipment can be considerable, and it would be very costly for an ordinary household to pay for this alone.
– The Norwegian authorities ought to provide financial support to help with this cleansing. Sweden has established regulations for financial support in such cases, added Frengstad.

Contact at NTNU: Bjørn Frengstad
Tel: +47 73 59 68 33
Email: bjorn.frengstad@geo.ntnu.no