Samples and Visits
Pure Paani is visiting a series of target communities in order to learn more about what people think about their drinking water. Topics of interest include source dependability, source quality, treatment cost and treatment convenience. While many wards present potential applicable communities, those with focus factors above 4 present the highest priority for visits.
During visits, Pure Paani collects multiple water samples from different sources of drinking water. These sources include government taps, water ATMs, borewells and prepackaged bottles. The team of analysts then incubates a petrifilm (ready-made petridish) inoculated with 1 mL of each sample. In the map above, each relevant sample icon, when clicked, presents a photo of the corresponding dish after incubation. The resulting information tab also provides the quantity of Coliform colony forming units (CFU) read from each dish as well as the concentration of total dissolved solids (TDS) in each sample. The quantity of Coliform CFUs is read from each petrifilm according to the 3M interpretation guide.
There is a particularly jarring pattern by which samples from otherwise clean sources (Water ATMs, some taps) are shown to be highly contaminated when collected from private, household containers. That is, while residents are getting water that's been properly treated to remove biological pathogens, they are reintroducing contamination back into their water via their own storage equipment. One example of this trend is presented when comparing sample 45.14 to sample 45.03 (searchable from the left-hand toolbar), which present Water ATM samples collected directly from the source and from a household container, respectively.
This sheds lights on the large portion of the water distribution chain during which a considerable risk of contamination is present. This includes all processes before and after conventional treatment methods, if any, are applied. While many municipalities address this issue by maintaining a minimum threshold of active chlorine along the distribution chain, this is a feature of water infrustrucutr to which many of Bangalore's residents do not have access.