The quality of rainwater collected from roofs in the aspect of the possibility of their economic use

Abstract. The large variability in rainwater quality both in time and location as well as the relatively small number of tests make the preliminary assessment of economic exploitation of these waters difficult. Determining the relation between the conditions and location of rainwater collection and rainwater quality would help to indicate the range of options for rainwater use as well as parameters that require improvement.

The aim of the presented article is to establish chosen physical, chemical and microbiological parameters of rainwater and, based on the results obtained, to determine the possibilities for a safe use of these waters in households. The research had been carried out for two years. Samples of chosen rainfalls were collected from spring to autumn from the following roofing materials: concrete roof tiles, ceramic roof tiles, zinc coated metal sheets and epoxy coated. The physical, chemical and microbiological quality assessment has been conducted basing on the following parameters: reaction, turbidity, electrical conductivity, concentration of biogenic compounds, concentration of chosen elements, number of Escherichia coli as well as number faecal streptococci.

A significant bacterial contamination, a decreased pH and an increased turbidity of rainwaters were identified, depending on the parameters of the roofing washed by rainfalls and the intensity and frequency of precipitation.