As part of a larger commercial building feasibility study, the water quality in five rainwater harvesting and greywater recycling systems is being tested. This includes monthly and seasonal sampling from rainwater and greywater tanks, prior to treatment, to examine any transient contamination. This testing was initiated after respondents from the larger survey expressed concerns around water quality and health-related issues.
This sampling has, so far, found nil or low microbial loads for parameters measured (E. coli, Campylobacter spp., Salmonella spp., Giardia spp., Cryptosporidium spp. and culturable Adenovirus). Levels of E. coli of 2,400 MPN/100 mL were detected in one greywater sample, while the rainwater sampled from one of the buildings (C3) consistently contained E. coli in the range of 67–3,100 MPN/100 mL. All other microbial parameters were consistently negative. One sample of rainwater from another building (W1) had high levels of Zn, Fe, Ni and Pb. This variability of results is a typical characteristic of rainwater and greywater analysis. Overall, the measured parameters were generally within the expected ranges for rainwater and greywater.
A detailed health risk assessment will be carried out at the completion of sampling. However, the preliminary water quality results indicate suitability for non-potable use in commercial buildings and should not pose a risk to human health.
These perceived water quality and health issues may be an unfounded barrier, due to a lack of objective information. These preliminary results should help to alleviate this concern from the installation of more rainwater harvesting and greywater recycling systems in commercial buildings.