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What water analyses tell us?

Interpretation of water analyses (PDF: 610 kb)

Decisions 401/2001 and 461/2001 made by the Ministry of Social Affairs and Health determine the maximum allowed content of different impurities in household water in Finland. In the following, the origin and effects of each impurity are described. The maximum allowed/recommended content is given in brackets.
The most important parameters for filtration in a water analysis  are pH levels, iron, manganese, permanganate, conductivity, hardness and bacteria.


Big Blue filters with cartridges in the background. In the front on the right, FP2 filter with cartridges

See the brochure >UV disinfection (FI)
Heat-resistant and coliform (1 pcs/100 ml; 100 pcs/100ml)
In domestic wells, coliform bacteria deposits are one sign of surface waters accessing the well.
Deposits of heat-resistant coliform bacteria (E-coli) are a sign of feces-induced contamination. The well should be cleaned and disinfected.


pH levels (6.0.. 9.5 / 6.5.. 9.5)
See the brochure > Controlled raise of pH levels (FI)
pH indicates the acidity or alkalinity of water. Acidic natural waters with pH under 7 are common in Finland. The acidity is due to aggressive carbon dioxide that corrodes metal tubes and may thus cause water-induced damages. Low pH level in water can cause skin irritation. Greenish color in water equipment or hair is a sign of low pH values.


Conductivity and salts (2,500/400 µS/cm)

See brochure > Removal of salt, fluoride, nitrate and arsenic (FI)

Conductivity indicates the content of salt, such as NaCI, dissolved in water. High conductivity is a sign of an excessive amount of salt which is harmful to both health and water equipment due to corrosion.
Chloride causes unwanted taste in water and corrosion in water equipment when the levels reach 50–200 mg/l.
Natrium levels must not exceed 200 mg/l.
Excessive salt, nitrate, fluoride and arsenic, for example, can be removed with a special membrane method (model RO 650)


Colour (40 mg Pt/l) and odour
Clean water is colourless and odourless. Colour in water is usually caused by humus, iron and manganese, for example. Copper-containing water may get colorised very strongly when combined with a detergent. Odour in water may be caused by hydrogen sulfide, manganese and organic compounds, to name a few.


Sedimentation is caused by iron (causes colour changes from reddish to brown), manganese (dark in colour), hardness (light in colour, or brown when occurs together with iron), humus (yellowish green to brown), copper together with other compounds (blue-green).
Furthermore, sand may be found in a bore wells and trash or moss in surface waters.


KmnO4 figure (20/12 mg/l)
The KmnO4 figure indicates the amount of organic decaying substances in water. In Finland, this organic substance is typically humus, which affects both the look and taste of the water and may contribute to the forming of sedimentation. See brochure (FI)


Iron (0.4/0.2 mg/l)
Along with humus, iron (also known as rust) is one of the most common impurities found in wells. When the iron value exceeds 1 mg/l, a pungent, metallic taste and possibly crud may be detected.
Even smaller contents may cause colouration in sanitary rooms and laundry. Large amounts of iron may cause clogging in water equipment and rust pipes and dishes. See brochure


Manganese (0.1/0.05 mg/l)

See brochure  |  Further information on the impact of manganese on intelligence quotient (FI)

Manganese is typically found together with iron, but occasionally also separately. The harmful properties of manganese are the same as with iron, but they emerge at lower contents.


Hardness (Suggestive Ca 100/50 mg/l)
See brochure > Removal of manganese and humus (FI)

Hardness refers to calcium and magnesium contents dissolved in water, both useful for health. However, hardness creates so-called fur in heat exchangers and other water equipment, which undermines heat transfer. In hard water, more detergent is needed than in soft water. Water is considered hard when its hardness value exceeds 10°dH.


Alkalinity indicates the buffer capacity of water and it is the sum of compounds of alkaline behavior: hydroxide, carbonate and bicarbonate.


Fluoride (1.5 mg/l)
See brochure > Removal of salt, fluoride, nitrate and arsenic (FI)

Fluoride originates in soil. Excessive fluoride causes disruption with tooth enamel formation.


Nitrogen compounds (NH4 0.5 mg/l; NO3 50 mg/l; NO2 0.5 mg/l)

See brochure > Removal of salt, fluoride, nitrate and arsenic (FI)

Nitrogen compounds end up in water through the decomposition of organic material, from fertilizers and with sewage. Ammonium impairs the odour and taste of water and increases corrosion. Small children and pregnant women, in particular, should avoid water with high nitrate contents.


Copper (2,0 mg/l)
See brochure > Controlled pH raise (FI)

Copper usually originates in pipes due to dissolution caused by low pH levels. Copper contents are higher in hot-water pipes than in cold-water pipes. Copper causes metallic flavour in water, contributes to corrosion and causes greenish colour in water equipment and hair.


Arsenic and uranium 

Some of the heavy metals, such as zinc, are indispensable micronutrients, while others are environmental toxins, including lead, uranium, cadmium and arsenic.
In addition to causing a risk of cancer, arsenic in drinking water may aggravate the impacts of smoking and prevent the natural self-healing mechanism of DNA. See a link to the original publication. Heavy metals originate in soil or bedrock or different emissions. Uranium is known to increase the calcium, phosphate and glucose contents in urine and contribute to the progress of osteoporosis.
 See brochure (FI)


Radon (100/300 Bq/l)
See brochure > Removal of radon and uranium (FI)

Radon is a gaseous radionuclide that is commonly found in bedrock in Finland and Sweden at least; readings of 70,000 Becquerel/l have been measured in water in drilled wells.
Radon increases the risk of cancer to a significant extent in case of intensive exposure. Radon commonly occurs together with uranium. Radon does not occur in well-aerated surface wells.

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