Water Supply Continuity, Frequency, and Health Gains: Ten-year Evidence from Hubli-Dharwad, India

Intermittent water supplies (IWS) serve >1 billion people globally and can transmit waterborne infections. How often and for how long supply is delivered varies between and within IWS systems. The UN Sustainable Development Goals target having water “available when needed” for ≥12 hours/day or ≥4 days/week but there are scarce data on how supply frequency/duration within IWS affect health outcomes. We conducted a matched study in Hubli-Dharwad, India, a city served partially by continuous water supply (CWS) since 2007 and partially by IWS. We enrolled 2220 CWS and 2218 IWS households matched on socioeconomics and sanitation. We compared diarrhea prevalence in children <5 years and typhoid fever incidence between households with different water supply characteristics using generalized linear models with robust standard errors and adjusting for socio-demographics and sanitation. Among IWS households, the median supply frequency was every 8 days (interquartile range [IQR]=7-8), and the median supply duration was 4 hours (IQR=3-5). IWS households had 36% higher prevalence of child diarrhea (prevalence ratio [PR]=1.36, 1.00-1.84) and 78% more typhoid fever cases (cumulative incidence ratio [CIR]=1.78, 1.05-3.02) than CWS households. IWS households meeting the UN criterion and those in the top quintiles of supply frequency and duration (receiving water once every 1-6 days or for 7-24 hours per supply cycle) had similar health outcomes as CWS households. IWS households below the UN criterion had higher diarrhea prevalence (PR=1.41, 1.03-1.93) and more typhoid fever cases (CIR=1.93, 1.15-3.22) than CWS households, as well as more typhoid fever cases than IWS households meeting the criterion (CIR=3.66, 1.37-9.79). IWS households in the bottom quintiles of supply frequency and duration (receiving water once every 9-15 days or for ≤3 hours per supply cycle) had 45-72% higher child diarrhea prevalence and twice as many typhoid fever cases than CWS households (p-values<0.05). These findings support global efforts to implement CWS. Our results also highlight that increasing supply frequency and duration in IWS systems in the interim can deliver health benefits, and the UN criterion of having “water available when needed” improves health.