Conference on Environmental Science and Technology

The total freshwater resources available in Poland are relatively scarce and characterised by seasonal and area variability. They amount to about 1600 m3 per person per year which is below the water stress level (1700 m3). Only the Czech Republic, Cyprus, and Malta have lower water resources in Europe than Poland. The average annual precipitation in Warsaw in 2023 was 572.0 mm, compared to 656.2 mm in Poland. Rainfall in Poland allows it to be harvested, treated and reused in households. According to Polish law, apart from using rainwater for irrigating the garden, storing it for reuse in households for flushing toilets, laundry, and other similar purposes is also possible. Such use involves the construction of an appropriate installation. Rainwater can be collected e.g. from roofs. The available research shows that quality of rainwater depends, among other things, on the roof’s material, its location and size, the concentrations of chemical pollutants in the surroundings and in rainwater, as well as the time of the year. For the study, rainwater was collected from three types of roofs: bituminous, tinware and eternit located in the surroundings of Warsaw. At the same time, clean precipitation was collected as well. The following parameters were analysed in rainwater: pH, alkalinity, conductivity, colour, turbidity, COD, BOD5, chlorides, sulphates, nitrates, nitrites, ammonia, and phosphates. The study confirmed that the collected rainwater has differences in their composition. Their quality, indeed, depends on the material of the roof and its location, among other things. To be reused, they must be subjected to treatment processes.