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Control Of Drinking Water


Drinking water main constituents


A high color indicates that the water is colorless, but more or less yellowish. This yellowing is usually caused by a high content of organic matter - humus - and will therefore also be found later in the analysis by high NVOC value.

Resignation: Max. 5 mg Pt/l, however, 10 mg Pt / l permitted if the color is due to humus.

Wiring: Max. 15 mg Pt/l.



The word turbidity may the Danish people call ambiguity and is measured in FTU = Formazin Turbidity Units that refers to some standard solutions with formazin. High turbidity means that the water is cloudy. Turbidity may not be immediately detected by the naked eye as it can be about fine particles - colloids. If the treated water has high iron or manganese content, it will also recorded as increased turbidity.

Resignation: Max. 0,3 FTU.

Wiring: Max. 1 FTU.


Smell and Taste

Drinking water should be palatable and free of odor, apart from the smell and taste of any chlorine. Smell and taste specified on water analysis as a subjective assessment.


For high temperature of drinking water affects the taste experience and can create a risk of bacterial growth.There are no water quality requirements for temperature, but a note in the notice: "It is desirable that the water is not more than 12 ° C at the faucet."



pH is an expression of the acidity of the water, so that a pH value of 7 corresponds to neutral, above 7, the water is alkaline, or alkaline, and below 7 is acidic.

Resignation: 7-8,5.

 Billede: 1261



Conductivity is as evaporation residue (see below) refers to the contents of dissolved salts and used as a quick method to control salinity.

Resignation: Min. 30 mS/m.

Wiring: Min. 30 mS/m.



NVOC is an abbreviation for Non Volatile Organic Carbon - no volatile organic carbon - and is called pool parameter, that is a size that indicates the presence of multiple substances or groups to which the carbon is included as organic carbon. Most often NVOC expressed natural occurrence of, inter alia, humic substances, but can also be a sign of contamination. NVOC replaces the previously measured "permanganattal".

Resignation: Max. 4 mg C/l.

Wiring: Max. 4 mg C/l.


Evaporation residue

The residue is an overall impression of the contents of dissolved salts. It is characteristic that the groundwater has a higher value than surface water. A certain content of salts, helps to make the water tasty, but exceeded the required value, the water is usually not suitable for drinking water.

Resignation: Max. 1500 mg/l.

Wiring: Max. 1500 mg/l.


Calcium, Ca2+

Calcium is a hardness together with magnesium, and there are no separate requirement, but a note in the notice: "The content should not exceed 200 mg / l".

 Billede: 1261


Magnesium, Mg2+

Magnesium is a hardness together with calcium. For high levels can cause taste problems and can be slightly laxative.

Resignation: Max. 50 mg Mg/l.

Wiring: Max. 50 mg Mg/l.


Hardness, total

As explained above, the calcium and magnesium water total hardness - a large content results in hard water, a small soft water. The hardness measured in German degrees of hardness, ° dH, and the water can be characterized by the following scale:

0°-4° dH very soft

4°-8° dH soft

8°-12° dH medium hard

12°-18° dH pretty hard

18°-30° dH hard

above 30° dH very hard

Soft water can cause corrosion problems while hard water causes major soap consumption and kalkudfældninger. There are no separate water quality requirements for hardness, but a note in the notice: "Water hardness should be between 5° and 30°"

 Billede: 1261


Sodium, Na+

Sodium is usually comes along with chloride or bicarbonate, depending on the water type. Increased sodium salt gives flavor and affecting possibly blood pressure diseases.

Resignation: Max. 175 mg Na/l.

Wiring: Max. 175 mg Na/l.


Potassium, K+

The presence of potassium in drinking water may indicate contamination, but there is indeed no taste or health hazards resulting from high potassium content.

Resignation: Max. 10 mg K/l.

Wiring: Max. 10 mg K/l.


Ammonium, NH4

The presence of ammonium may be signs of contamination, but often have other causes. Raw water ammonium will by proper water treatment traded via nitrite to nitrate under quite much oxygen and involvement of microorganisms. In clean water chemical balance should not contain ammonium as a possible incomplete reaction will continue unchecked in the distribution system with, among other nitrite formation to follow. If the water is not filtered at the waterworks, the ammonium content up to 0.50 mg / l is acceptable, but nitrite must then be checked on the grid. In water treatment filtration requirement:

Resignation: Max. 0,05 mg NH4/l.

Wiring: Max. 0,05 mg NH4/l.


Iron, Fe

Iron is the substance that you primarily want to remove by water treatment, since too high in the clean water provides the most conspicuous genes: deposits in wiring and fittings genes by laundry and deposits in basins and sinks, bad taste and turbidity. Increased iron content is rarely harmful, although in unfortunate circumstances - anoxic conditions - can be made for growth of iron bacteria. Some places in the country can be HUMINT iron bound - that is bound to organic humic acids, and it may then be difficult at a traditional aeration and filtration to remove the iron completely.

Resignation: Max. 0,1 mg Fe/l.

Wiring: Max. 0,2 mg Fe/l.

Billede: 1261

Manganese, Mn

Manganese often occurs together with iron and causes similar disadvantages as iron (see above), but in lesser amounts. Manganese in the distribution system can appear as a black, slightly oily greasy substance.The treated water should be completely free of manganese.

Resignation: Max. 0,02 mg Mn/l.

Wiring: Max. 0,05 mg Mn/l


Bicarbonate, HCO3

Bikarbonatindholdet associated with the concept of "temporary hardness", since the area of hårdhedsdannerne (see "Calcium" and "magnesium"), which occur in particular calcium bicarbonate could be removed from service water by boiling and precipitate as scale. There are no water quality requirements for bicarbonate, but when certain content is of importance to the pH, there is a point in the notice: "The content should be above 100 mg / l".

 Billede: 1261

Chloride, Cl-

Excess chloride can cause taste problems - water tastes salty at ca. 400 mg / l, the risk of corrosion, with consequent solution of the heavy metal corrosion in hot water systems, and more. Especially in Denmark, where there is potential for saltwater intrusion and saline soil layers, it is important to keep the chloride content in each drilling under control.

Resignation: Max. 250 mg Cl/l.

Wiring: Max. 250 mg Cl/l.


Sulphate, SO4

Elevated sulfate content which can cause flavor problems chloride while in the case of magnesium a laxative effect. In addition, sulfate under unfortunate circumstances be reduced to the smelly and toxic gas hydrogen sulfide, for example, under anaerobic conditions in hot water systems.

Resignation: Max. 250 mg SO4/l.

Wiring: Max. 250 mg SO4/l.


Nitrate, NO3

Excessive levels of nitrate in drinking water can be harmful, especially for infants, since nitrates in children's digestive system causes the oxygen supply via the red blood cells is reduced, and the children become "cyanotic" - "blue" - children. It also demonstrated a certain increase in the number of stomach cancer in patients from areas with high nitrate levels in drinking water. Nitrate in pure water, in amounts less than 5-10 mg / l, is normal and usually originate from ammoniumomsætning (see "Ammonium").Nitrate in raw water can - together with the presence of nitrites - be signs of pollution, and the water must then be evaluated with care. In some localities can nitrate may be of geological origin, partly because of seepage through soil layers which do not reduce or withhold nitrate. It's important to keep stricter oversight of water microbiological condition because organic micro pollutants, especially pesticides, so also occur.

Resignation: Max. 50 mg NO3/l.

Wiring: Max. 50 mg NO3/l.


Nitrite, NO2

Nitrite in water is usually an unstable compound which is derived from conversion of ammonium in one way or another. If nitrite detected even in trace amounts, in a fresh sample of raw water, it is evidence of contamination and microbiological activity. The presence of nitrite in pure water does not, however, mean pollution, but can occur under certain operating conditions. It is mentioned in the notice as an option due to the renewal of the filter materials to add: "but should be limited as much as possible." High nitrite content may also impede blood oxygen uptake.

Resignation: Max. 0,01 mg NO2/l, however, allowed up to 0.10 mg NO2 / l if the requirement of wiring are met.

Wiring: Max. 0,10 mg NO2/l.

Billede: 1261 


Total phosphorus, P

The presence of phosphorus in both raw water as clean water may indicate contamination - as a result of the grain surface / wastewater, but can also have a geological origin. In particular, deep wells with a certain iron content, a portion of the iron often be bound as phosphate, which in this case will be retained in the filters, if these are satisfactory. There should therefore be no phosphorus in clean water, not even as a trace. Note that the parameter specifies the content of phosphorus P, where the former could be given as phosphate PO4.

Resignation: Max. 0,15 mg P/l.

Wiring: Max. 0,15 mg P/l



Fluoride in drinking water works preventive against caries - tooth decay, and dentists believe that the most favorable content for this purpose is approximately 1.2 mg / l. On the other hand is considered a just a little higher content to be harmful.

Resignation: Max. 1,5 mg F/l.

Wiring: Max. 1,5 mg F/l.


Oxygen, O2

As outlined in the previous parameters oxygenated water during water treatment to filter out iron and manganese as well as transform ammonium, and this oxidation must be so strong that the wiring still 5 mg / l oxygen left. The oxygen ensures water palatability and prevents the growth of bacteria that can grow under anoxic - anaerobic - conditions.

Wiring: Min. 5 mg O2/l.


Aggressive carbon dioxide, CO2

Aggressive groundwater - containing aggressive CO2 - occurs especially in Jutland, where the soil is lime poor and Surface low salt. Common to both types is low water hardness and pH. The water must be treated to the finished water does not contain aggressive CO2, which may be corrosive to iron and concrete. On the other hand, the water may well contain a certain amount of free carbon dioxide, which helps to give the water a fresh taste. The amount is also dependent on the balance bicarbonate / carbonate and pH.

Resignation: Max. 2 mg aggressive CO2/l (Not measurable).

Wiring: Max. 2 mg aggressive CO2/l (Not measurable).


Hydrogen sulfide, H2S

Hydrogen sulphide is a smelly - like rotten eggs - and poisonous gas that occurs in some raw water types, but must be removed early in water treatment by oxidation. As described under "Sulfate", hydrogen sulphide can occur under adverse conditions in the grid especially in hot water.

Resignation: Max. 0,05 mg H2S/l (Not measurable).

Wiring: Max. 0,05 mg H2S/l (Not measurable).

 Billede: 1261


Methane, CH4

Methane is an odorless, explosive gas that occurs in the raw water in some parts of the country. It must be removed early in the treatment water by aeration or blowing, since it can give bacteriological problems especially in the waterworks.

Resignation: Max. 0,01 mg CH4/l (Not measurable).

Wiring: Max. 0,01 mg CH4/l (Not measurable).



Mikrobiologiske parametre:


Coliform bacteria

This group of bacteria is usually not pathogenic in itself, but thrive in the same places as the disease-causing bacteria and are therefore called "indicator bacteria". Detection of coliform bacteria taken as a sign of pollution, and the presence shall be further study.

Resignation: i.m. pr. 100 ml (Not measurable).

Wiring: i.m. pr. 100 ml (Not measurable).


Escherichia coli (E. coli)

Coli occurs in warm-blooded animal and human intestinal tract, and occurrence in drinking water indicates a fresh contamination with inflow from sewage, septic tank, manure, slurry stores and the like, with a risk for the presence of pathogenic bacteria. Parameter was in the previous publication called "thermotolerant coliforms".

Resignation: i.m. pr. 100 ml (Not measurable).

Wiring: i.m. pr. 100 ml (Not measurable).


Plate count at 37° C

Bacteria can grow at body temperature, can be pathogenic or accompanied by pathogenic bacteria, and there has never been tolerated more than a few pieces of good drinking water as it leaves the waterworks. On the wiring harness higher values may occur, especially in large installations.

Resignation: Max. 5 pr. ml.

Wiring: Max. 20 pr. ml.


Plate count at 22° C

This plate count expresses the number of "cold-loving" bacteria - soil and water bacteria, putrefaction bacteria with more that can be naturally occurring in nature, and living by the water content of organic matter. They are rarely pathogenic, but may not occur in the large amount, both with respect to weak people.It is important to observe a sudden change in the bacteria count. The bacterial counts were previously measured as "Plate count at 21 ° C", but it's the same group of bacteria that grows.

Resignation: Max. 50 pr. ml.

Wiring: Max. 200 pr. ml.



Enterococci are intestinal bacteria - fecal streptococci, and occurrence indicates just as E. coli fecal contamination of water from sewage, manure or the like. After a transitional period of two years measured enterococci only in the presence of E. coli.

Resignation: i.m. pr. 100 ml (Not measurable).

Wiring: i.m. pr. 100 ml (Not measurable).


Clostridium perfringens, including spores

Clostridium perfringens is a spore-forming intestinal bacterium in the presence indicates an older fecal contamination. The parameter is only determined by surface effects.

Resignation: i.m. pr. 50 ml (Not measurable).

Wiring: i.m. pr. 50 ml (Not measurable).