Underground and surface waters in Dalmatia (Southern Croatia) have relatively preserved their natural characteristics since the greatest agglomeration of population and industry is located along the coast. The danger of pollution with fecal microorganism and products of biological decomposition is the most immediate problem but can be efficiently eliminated by water chlorination. The ecological need to sum up the work on water quality examination and estimation of future water quality trends resulted in water quality monitoring, i.e. in human health monitoring. It is necessary for large number of analytical and ecological health data to organize them from the informatical aspect into databases, the relational database for chemical analysis studying (the difference between anions sum and hardness) as methodological base for studying the ecological factors that influence human health defined in this paper. Results used for the prototype implementation subsystem of the chemical water analysis control are based on the investigations of Water Examination Department of the Public Health Institute of the Split-Dalmatian County (Croatia). Over 3400 data are comprised what is the sufficient examination sample. The software used included Win '95, Mo '97, and Paradox 4,5, while the hardware used included Pentium II 300 MHz, floppy, 128 MB RAM HDD 4,3 GB, CD x 24, HP DeskJet 710C.