New findings in the field of swimming pool water and bath water hygiene as well as technical development of the corresponding treatment processes necessitated a revision of the standard series DIN 19643. As a result the standards - DIN 19643-1 "Treatment of water of swimming pools and baths - Part 1: General requirements"; - DIN 19643-2 "Treatment of water of swimming pools and baths - Part 2: Combinations of process with fixed bed filters and precoat filters"; - DIN 19643-3 ("Treatment of water of swimming pools and baths - Part 3: Combinations of process with ozonization"); - DIN 19643-4 "Treatment of water of swimming pools and baths - Part 4: Combinations of process with ultrafiltration" which have been prepared by Working Committee NA 119-04-13 AA "Schwimmbeckenwasser" ("Pool water") at the Water Practice Standards Committee (NAW) are now available. Part 1 applies for the treatment of water, including sea water, mineral water, medicinal water, brine (including artificial brine) and thermal water in swimming pools and bathing facilities. It does not apply for the treatment of water in family pools and water in facilities with biologically treated water. The aim of this document is to ensure good, consistent quality of pool water with regard to hygiene, safety and aesthetics so there are no concerns regarding damage to human health, especially by pathogens. In this respect the well-being of bathers (for example, by minimizing secondary reaction products of disinfection) shall also be considered. For this purpose, water quality, dimensioning, operating and control requirements are specified. Treatment requirements to achieve this aim are stated.