Investigation of Microbiological Quality Changes of Roof-Harvested Rainwater Stored in the Tanks

Abstract

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.

Evaluation of the Influence of Catchment Parameters on the Required Size of a Stormwater Infiltration Facility

“…Considering the range of challenges facing global communities, solving the problem of stormwater management cannot be done without getting closer to achieving the Sustainable Development Goals [15]. Particular attention should be paid to the need to ensure the health [16] and well-being [17] of people in the drained area and to guarantee universal access to potable water [18]. Equally important are the issues of creating sustainable cities and communities [19], responsible consumption and production [20], and protecting life on land, for example, by preventing flooding [21,22] and sewer overload [23].…”

Stormwater Harvesting from Roof Catchments: A Review of Design, Efficiency, and Sustainability

“…The concrete roof had a beneficial influence on hardness, EC, pH, and alkalinity compared to the other roof types [29]. Rainwater collected in the spring and autumn with a flat roof covered with epoxy resin had the poorest microbiological quality [30]. When harvesting rainwater for non-drinking purposes, a stabilized soil cistern was considered an alternative [28].…”

“…Rainwater retention can also enhance the physicochemical and microbiological quality of rainwater collected from any roofing material, regardless of the season or the roofing material used [19]. Closed tanks with no fresh rainwater intake for at least six weeks are necessary to improve the water quality [30]. The rainwater was not suitable for drinking purposes.…”

“…In the studies reviewed, the TSS, turbidity, and COD removal reached up to 72.75 ± 4.27%, 52.71 ± 33.26%, and 63.61 ± 19.26% (mean ± SD), respectively. One reviewed study proclaimed that a 100% removal of E. coli removal was observed after six weeks of storage at 12 • C [30]. Most of the treated water experiences an increase in pH, with one achieving a 52.63% increase.…”

A New Method for Selecting the Geometry of Systems for Surface Infiltration of Stormwater with Retention

“…In this case, the goal is no longer to use and remove resources but to preserve them in use and revive them [15,16]. Rainwater harvesting systems are becoming very popular [17,18]. The possibility of using rainwater as an energy source is also being analyzed [19].…”