The sounds of metallic clicks followed by the high-pitched whirring of rotating mechanical parts emanate from the screened garage windows of the houses along the alley. Under the hard, white light of the street lamps, I check my watch – 5:15 am. The sounds tell David and I that the morning water supply has begun. With each subsequent pump click, we grow more frantic. Our own suction pump is still not working. Each house is armed with such a pump to extract as much water from the pipelines as possible during the short two-hour supply window. We rose from our beds at 3:30 am and brought our own suction pump to this urban Indian back-alley to siphon our own water for quality testing. With a few more minutes of tinkering, David has our pump awake and we too begin drawing water. Every minute for the first 30 minutes, David collects a small 10 milliliter sample and measures the cloudiness, called turbidity. At the same rate, I collect half-liter samples in plastic bottles that we will later test for microbes
The first 30 minutes pass in a blur of activity, and then things slow down. David reduces his sampling frequency to every 2 minutes, and I decrease my own collection rate to one sample every 10 minutes for the next two hours. Slowing down brings no relief as the waiting only heightens our sleep-deprived. In between samples, I snack on the hoard of gas station food we purchased at the local 24x7 convenience store. This has been our breakfast each day of the last three as we’ve sampled drinking water from the pipe buried in this alley. We are as amused by our junk food haul as the cashier at the small store. He has to be wondering what these foreigners in reflective safety vests are doing buying a small fortune worth of gas station food from him every morning at 4 am.
David and I, both engineers, have been travelling in and out of India for the last few years studying the water distribution, water quality, and human health effects of intentionally short bursts of water supply. Called intermittent water supply, this water delivery strategy is used to ration drinking water in much of the world. Rather than keeping water pipes consistently full of treated water, they are filled only for a few hours each day, during which time residents take the water they need and store it in large tanks in their houses. While intermittent supply seems like a good solution, it has several shortcomings. First, such supplies are always in transition with the pipes filling and emptying. This makes our traditional design approaches, based on steady operating conditions, irrelevant and subsequently operating such systems is notoriously difficult. Second, because the drinking water pipes are often empty, contaminated water can easily leak into the network through cracks and holes in the pipelines. The suction pumps used by households to extract water likely exacerbate this contamination by sucking contaminated water in at an even greater rate. Unfortunately, this contamination can render the highest level of access to clean drinking water, a piped supply, unsafe. The small amount of data we’ve collected in the last three days corroborates the hypothesis. We’ve noticed that in the first 30 minutes of supply, when clean water first enters the pipes and washes them out, the turbidity and microbe measurements are high. It’s hard to say anything conclusive with only two days of data from one site, but so far it seems that contamination is plausible.
My inspections of the alley in the last few days further strengthens the plausibility of this narrative. Even through bleary eyes, it’s impossible not to notice the manholes indicating that a sewer line, collecting raw sewage from each house, is likely buried within a few feet of the waterline. The downspouts coming from the roofs of each house are routed into the sewer manholes. It doesn’t take long before I’m imagining monsoon rains pouring down the spouts and into the sewer, flooding the manholes and alley. Raw sewage mixed with rain percolates through the ground and leaks into the water pipes. The water supply switches on and clean water flushes gallons of toxic water into household storage tanks. Hundreds in the neighborhood fall ill with a waterborne disease.
It’s potential scenes like this that motivate me, a self-proclaimed public health engineer, to get out of bed at 3 am for days on end. The worst part would be that the sick were betrayed by a piped water supply that was supposed to keep them safe. We as engineers can’t let that happen.