Groundwater quality

Humans, animals and plants need a wide range of minerals. A too high or too low intake can be harmful. Water is our most important nutrient. It is also an excellent solvent, interacting with materials in the layers of the subsurface and absorbing minerals as it flows along.
Water is an excellent solvent for minerals in the rocks. Photo: T. Mortensen.

Usually groundwater has a far higher mineral content than surface water. In olden days, individuals lived often on one-sided diets, so it is no surprise that the mineral-rich spring water could be perceived as have healing powers. Groundwater is also less like to contain pathogens than water from streams and lakes, so any pilgrim suffering from chronic diarrhea would be in good health as long as they drank only spring water.

Most common elements

Labels on bottled naturally sourced mineral water indicate the most common elements found in ground water. Modern methods of water analysis can detect nearly all the elements, even if their concentrations are extremely low. Some of these elements may have negative health effects, even in trace amounts, such as arsenic, antimony, lead, and cadmium.  Fortunately, it is rare that such elements are found in significant concentrations in ground water in Norway.

On the other hand, in Norway's granites and bright gneisses groundwater may display an elevated content of fluorine, radon and uranium. These are natural chemical substances without taste, odor or color, so all well owners are advised to get their drinking water analyzed. In addition, one must make sure that the well is located and designed so that the water is not exposed to bacterial contamination from wastewater, livestock and wild animals.

Inorganic water chemistry

NGU has examined the inorganic water chemistry in a variety of private and public drinking water wells and the public water supply. Iron and manganese are the most common water quality problems in the ground water found in quaternary deposits and in bedrock. Hard water is also fairly common. However, these quantities have only a practical or aesthetic significance and can be detected without water analysis.

For high concentrations of the radioactive radon gas, one in seven bedrock wells display high levels, but very rarely is this gas found in wells dug into loose rock material. Concentrations of fluoride of 1.5 mg/l, the levels which can damage children's teeth, has also found in one of seven wells in bedrock. Uranium, as it occurs in nature, is a heavy metal that is not very radioactive, but may harmful if ingested long-term.  The World Health Organization suggests limit of 0.030 mg/l, so water from one in eight privately owned bedrock wells display uranium over levels that are considered safe.

Placement of the wells

Several surveys of the bacterial levels in the private water supplies, conducted by NGU, by the Norwegian Food Safety Authority or the municipalities, demonstrate that over half of the wells contain the bacteria that suggest human or animal fecal contamination. This is due to placement of the wells close to leaking sewage systems, barns or pastures, and inadequate protection from surface water. The addition of small amounts of bacteria will contaminate water and can destroy a well which should only deliver clear, clean ground water.

Ground water is usually a good option for a drinking water supply for smaller towns and villages, as well as isolated settlements. The use of groundwater is, however, not entirely without challenges. NGU will continue its work assembling and disseminating knowledge that ensures a safe drinking water supply.

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