The large temporal and spatial variability of rainwater quality, as well as the relatively small number of tests, makes the preliminary assessment of its economic exploitation difficult. Determining the relationship between the conditions and location of rainwater collection and rainwater quality would help indicate the range of options for rainwater use, as well as the parameters that require improvement. The aim of the presented article is to establish the physical, chemical, and microbiological parameters of different rainwater sources and, from the results obtained, determine the possibilities for its safe use in households. The research was carried out for two years. Samples of rainfall were collected from spring to fall from the following roofing materials: Concrete roof tiles, ceramic roof tiles, galvanized steel sheet, and epoxy-coated terrace. The physical, chemical, and microbiological quality were assessed on the basis of the pH, turbidity, electrical conductivity, the concentration of biogenic compounds, the concentration of chosen elements, the number of Escherichia coli, and the number of fecal streptococci. Significant bacterial contamination, decreased pH, and increased turbidity were identified in the water, depending on the parameters of the roofing washed by the rainfall and the intensity and frequency of precipitation.

A common economic use of rainwater is the basis for strategies that will allow the water sector to adapt to progressive climate change. Rainwater is a basic part of water resources that ensures the renewal of the surface and groundwater, therefore they should be protected against pollution and be managed and used in places of rainfall. This is particularly true for heavily urbanized, agricultural and industrial areas. Stormwater collection and storage systems have been introduced in many countries [1]. The water obtained in this way is a valuable source of fresh water, thanks to which it is possible to reduce the demand for tap water by almost 60% or use it during periods of drought [1,2]. The idea of the sustainable management of water resources and the increasing ecological consciousness of society have allowed installations for the collection and use of rainwater in residential houses and public buildings to become an increasingly popular phenomenon [3,4]. The research and assessment of rainwater quality is a guarantee of safety for its users. The article presents the results of research on the physical and chemical quality of rainwater collected directly from precipitation. Samples for research were collected in a suburban area during March-November 2015. The pH, turbidity, permanganate index, OWO, nitrogen compounds, phosphates, oxygen content, acidity, basicity, conductivity, hardness, and heavy metals content were determined. The obtained results were the basis for indicating the possibility of using rainwater for various economic purposes.

Growing areas of sealed surfaces, rising water needs due to industry development, increasing populations, and climatic changes affect precipitation patterns and form a vision of the future in which meteoric water storage may become almost an obligatory activity. The aim of this paper was to identify the amounts and, to some degree, the quality of microorganisms present in rainwater collected from different types of rooftops of utility buildings in the spring-summer season. Apart from the classic culture plate method complemented by flow cytometry. The results of performed analyses explicitly show that rainwater collected from rooftops and directly from air prove to be microbially contaminated to a substantial degree, which includes pathogenic coliforms and faecal streptococci. Waters collected after dry periods also contained bacteria like Clostridium perfingens. The findings rule out the possibility of using rainwater collected from roof surfaces of utility buildings before its treatment.

Rainwater has been found to be a valuable source of drinking water in Europe, especially in such crisis situations as those caused by contamination of water uptake into water supply systems, large-scale floods or terrorist attacks (e.g., biological weapons). The microbiological quality of water plays a significant role, which is directly related to the potential health risks associated with harvested rainwater (including rainwater stored in the tanks). Microbial contamination is commonly found in rainwater. However, in the literature, detailed results of qualitative and quantitative microbiological assessments are sparse and remain unexplored. Therefore, the aim of this study was to investigate and analyze changes in the microbiological quality of roof-harvested rainwater stored in the tanks, depending on the collection conditions (type of roof surface), storage duration and season. Authors elucidate that conditions such as storage duration, the season in which rainwater is collected, the roof-like surface types and morphology of the catchment area highly affect rainwater quality. This study showed that rainwater harvested from a galvanized steel sheet roof had the best microbial quality, regarding the lowest number of bacteria, while rainwater from a flat roof covered with epoxy resin was the worst. Further, it was detected that rainwater collected in autumn and spring obtained the best microbiological quality. Moreover, a decrease in the number of bacteria was observed in correlation to storage duration. The water became sanitary safe after six weeks of storage at 12 °C. Its use for purposes requiring drinking water quality before six weeks of storage required disinfection.

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