Bacteriological health threats to water in home wells

Bacterial infections that are due to consumption of poor quality water are still an important threat to human health and life. The aim of the article was to investigate the bacteriological threat of water from home wells. The results of water testing from individual wells constituted research material. On their basis, the health risk of fecal streptococci, coliforms and Escherichia coli was assessed and an attempt was made to assess the impact of pollution on the health of residents. The results of water testing in private wells showed unacceptable values for bacteriological pollution. A signifi cant health risk was found for fecal streptococci, coliforms and Escherichia coli. The authors pointed out the need to take extensive actions aimed at raising environmental and health awareness of the inhabitants in terms of water quality used for living purposes, in particular for consumption. 22 E. Wysowska, K. Kudlik, A. Kicińska regulations. Especially dangerous items are devices used for periodic collection or disposal of domestic and household sewage, the so-called septic tanks. Taking into account the facts quoted in the area of the municipal water and sewage enterprise, free check-ups were proposed as part of which residents had the opportunity to test the quality of water taken from their private home wells. On their basis, the potential risk resulting from the consumption of water contaminated with microbial pathogens, such as: (a) fecal streptococci (Enterococcus faecalis), (b) coli group bacteria and c) Escherichia coli (hereinafter E. coli). The study of the indicated groups of microorganisms is required in the monitoring of intakes used for the collective supply of drinking water (Regulation of the Minister of Health 2017). Materials and methods The collected research material included the results of testing water samples from individual wells with a total amount of n = 435 from a selected area of south-eastern Lesser Poland. For the purposes of this article, the communes where the research material was collected were marked with symbols A–J (Tab. 1), and the waters in which fecal streptococci, coliforms and Escherichia coli were analyzed were collected in 2015–2018. The analyzed water samples were taken from home wells, mostly dug wells. These wells use the shallowest, Quaternary water layer, characterized by low resistance to pollution originating from the land surface. Raw water samples came from wells that: i. are a reserve source of drinking water for households using the collective water supply system, ii. can be a basic source of drinking water for households using the collective water supply system, iii. are a source of drinking water for households within the range of the collective water supply system, but not using it, iv. are a basic source of drinking water for households outside the range of the collective water supply system. The voluntary nature of testing water from individual home wells and the related anonymity of the research results made it impossible to assign specifi c wells to the groups described above. However, this does not diminish the advisability of the pilot research on the water supply company and the appropriateness of further analysis. Of the 435 samples tested, 6 came from households located outside the area of activity of the collective water supply company and 14 samples were repeated, i.e. a repeat check-up was made after the well user’s report. The number of samples taken in individual communes together with the breakdown by years is presented in Table 1. Due to the fact that the samples were not collected cyclically from each of the communes over the analyzed period, and the sampling was previously a verifi cation test, a research sample consisting of 425 samples from the communes was selected for further analysis: A, B, C and D, in which the greatest number of water samples was taken. Other sampling sites were rejected due to the negligible number of well water samples taken in 2015–2018 (n ≤ 2). It is mentioned that the total number of rejected samples (n = 10) represents only about 2% of the total test sample (n = 435). In Table 1, the rejected samples were marked grey. Further analyses were made based on a selected research material consisting of 425 samples. Microbiological tests of water were made in the Accredited Water and Sewage Testing Laboratory, belonging to the water supply company making verifi cation tests, based on the PN-EN ISO 7889-2:2004, PN-EN ISO 9308-1:2014 Ap1:2017 standards. Characteristics of the study area From the total number of tested water samples (n = 425), 127 samples (areas B, C, D) came from agricultural areas, while agricultural or post-agricultural areas located on the outskirts of cities were home to:298 samples (areas A and D) (Fig. 1). The research areas (A–D) are geographically located in the part of the Carpathian Foothills of the Outer Western Carpathians, constituting mountainous, upland and river valleys with a diversifi ed terrain. They are located at altitudes from 270 up to 450 m above sea level (Kubal 2001). The geological structure of the area consists of tertiary formations: sandstones, shales and marls that were uplifted and folded. The area is located within the main structural unit of the Carpathians. Table 1. Quantities of well water samples taken in 2015–2018 Commune Number of samples taken (n) 2015 2016 2017 2018 Total