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Water Quality: Management, Sanitation and Investigation

Minimum requirements for the quality of untreated water
for the preparation of drinking water
The quality of the available untreated water must be so good, that reasonable effort can be used to convert it into drinking water which fulfils the valid rules and regulations. The upper limits of reasonable effort are defined in Europe for three categories of effort by the EG Guideline for Untreated Water [21]: they are also used in Germany therefore. As a rule, at least mesotrophic conditions are sought after in a lake or reservoir in order to encounter problems caused by development of algae quantities, oxygen starvation and re-dissolving processes. Nitrogen compounds and especially phosphor determine the trophy of the waters. Organic and inorganic pollutants (solvents heavy metals, nitrate) which cannot be removed from untreated water, or can only be removed with difficulty must not be found or may only be found below the limiting values of the valid Drinking Water Decree [24].

Table:  Examples for limiting values according to the German Drinking Water Decree [15], (Trinkwasserverordnung [15]) already guaranteed for untreated water

Criterion  Unit  Limiting value
Calcium  mg/L 500
Nitrate mg/L  50
Oxidizability (COD) mg/L  5
Aluminium mg/L  0,2
Mercury  mg/L  0,001
Pesticides (total)  mg/L  0,0005
PAK (total) mg/L  0,0002
PSM (indiv. subst) mg/L 0,0001


Richtlinie des Rates vom 16. Juni 1975 über die Qualitätsanforderungen an Oberflächenwasser für die Trinkwassergewinnung in den Mitgliedsstaaten (75/440/EWG): Amtsblatt der Europäischen Gemeinschaften, Nr. L 194/34-39, 25.07. 75 geändert 9. 10. 1979.

Trinkwasserverordnung in der Fassung vom 5. 12. 1990 BGBl. der BRD I

foundations: biology, limnology, chemistry

© | Dipl.-Biol. Hartmut Willmitzer |  31.07. 2000 | Copyright