By Fiona Burlig, Amir Jina and Anant Sudarshan
Via VoxDev
Over two billion people globally lack access to safe drinking water, leading to enormous health consequences: two billion cases of diarrhoea and half a million deaths among children under 5 annually (Dupas 2024). Nevertheless, the aspirational gold standard of piped, potable water access in developing countries is rarely present, with only 14% of rural households in low- and middle-income countries enjoying clean tap water in their homes. Moreover, even when piped infrastructure does exist, water flowing through the tap is often just as contaminated as local ground- and surface-water sources. All the while, children suffer the costs of contaminated water.
Can decentralised treatment and home delivery increase access to clean water?
On its face, there is an effective and very low-cost alternative: treating water in the house using chlorine tablets or solutions (Dupas et al. 2022). Unfortunately, chlorine is unpopular: in many experiments, less than half of households have been found to use chlorine even at zero price and demand plummets when households are asked to pay (Kremer et al. 2023), possibly because chlorine leaves an unpleasant aftertaste and is inconvenient to use.
We study a third option in an Indian setting. We began with the observation that, even though research and policy efforts have been directed towards piped water and point-of-use chlorine treatment, two solutions at opposite ends of the cost spectrum, the market for privately-treated and home-delivered water is growing rapidly in developing countries (Cordoba and Grabinsky 2020).
Naturally, this leads to the question: If a non-trivial share of the rural population is willing to pay for home delivery of bottled water over cheaper alternatives such as chlorine, could this technology play a role in increasing access to clean drinking water?
In Burlig et al. 2025, we describe the results of a randomised controlled trial in Odisha, India—covering 60,000 households in 120 villages—that aims to answer this question. We partnered with Spring Health India, a small firm in Odisha whose innovative product involves decentralised treatment of groundwater coupled with home delivery in large, sealed containers. Households can order 10 or 20 litre containers on demand, paying around INR 1.4 (US$0.012) per litre. We document three main results.
1. The demand for clean water is high at low prices, but falls off quickly as costs rise
First, we ask how demand for water varies with price. To do this, we randomise 40 villages into a discount treatment arm. Within these villages, we randomised individual houses to receive discounts on water ranging from 0 (the control) to 90%, which we implemented by running a special scheme in which households were given scratch cards, each revealing a randomised discount offer. We find that at very low prices, nearly all households order water, demonstrating that this method of delivering clean water could achieve near-complete coverage. However, we also document that demand falls off quickly as prices rise. Figure 1 shows how water orders respond to price. Notably, 89–90% of households ordered water at the lowest prices—even when they had access to chlorine and, in many cases, piped water.
An interesting feature of the pattern in Figure 1 is that we see as prices rise, demand falls but not because households uniformly buy less. Instead, we observe many households exit entirely—while those that remain continue to buy enough to cover most of their drinking water needs. This seems consistent with a population that understands that clean water is not very useful from a health point of view if it is only consumed half the time..
Figure 1: Probability of ordering clean water at varying prices
Notes: This figure shows that the vast majority of households ordered water at the lowest prices—even when they had access to chlorine and, in many cases, piped water. Conditional on ordering, households purchased enough to meet their entire drinking water needs, and this pattern held steady across months.
2. Clean water improves health and saves time
Next, we want to understand why households are ordering clean water. We surveyed households in the study several times over an approximately six-month period. We found that access to delivered clean water reduced self-reported illness by 23–62% and led to fewer missed workdays. It also reduced the time household members—often women—spent collecting water each day. These gains mirror prior work on the health impacts of safe water but are notable for their magnitude and consistency. Similar to other ways of provisioning clean water, the decentralised treatment and home delivery approach make individuals better off.
3. Households value clean water more than we thought
From the demand curve, we estimated the average willingness to pay for around 300 litres of water every month was INR 132 (or $20/year), roughly 1.5% of household expenditures. This is over 4.5 times larger than estimates from rural Kenya, based on travel costs to chlorine-treated springs (Kremer et al. 2011), and substantially higher than other valuations of chlorine-based point-of-use treatment. While comparisons across studies are difficult, an important part of the difference between what we find and prior studies is likely that we directly value clean water itself, rather than measuring willingness-to-pay for chlorine treatment or for water filters (Ashraf et al. 2010, Berry et al. 2020).
But willingness to pay is only part of the story. Although it may seem obvious that clean water is a valuable commodity, the poor have limited liquidity, many needs, and may not be fully informed of the benefits of clean water or quality of their existing sources; all of which can reduce willingness to pay. Thus, to better understand household valuation, we ran a second experiment treatment arm in 40 villages where rather than selling water at varying prices, we offered households the option of either ordering water or receiving a cash payment of varying amounts.
Strikingly, we found that households were willing to forgo substantial sums of money in favour of ordering clean water. Households assigned to the rebate arm routinely forwent INR 420/month (almost four times as much as their willingness to pay!) to continue receiving clean water, establishing a lower bound for their valuation. As in the discount arms, households who order water appear to order enough to meet their drinking needs and then convert the rest of their entitlement into cash.
Why do these valuation results matter? A high valuation for safe water offers one reason to support spending tax dollars on provisioning this good. The private market alone cannot fully address the clean water access problem; while water delivery can be privately profitable at high prices, relatively few households can afford it without subsidies. Indeed, a willingness to forgo cash for water—as we see in our research—may even suggest that reducing cash transfers to pay for water would align with public preferences; however, more research is needed to test this claim fully. Nevertheless, our evidence points to a higher valuation for clean water delivered directly than for in-home treatment via chlorination.
Lastly, we investigate cost-effectiveness of this clean water delivery approach. Figure 2 shows the results of this calculation. We estimate that the cost per Disability-Adjusted Life Year (DALY) of free clean water delivery in our setting is $71–226—well within global health cost-effectiveness thresholds. This is slightly more expensive per DALY than chlorine subsidies but delivers far higher take-up and thus higher social welfare.
Figure 2: Cost per DALY
Notes: Spring Health water is highly cost-effective under varying assumptions about water supply reliability, which households are subsidised, and whether the government is responsible for the fixed costs of supply. Chlorine from dispensers and via coupons handed out at maternal/child health centres is also highly cost-effective. While the cost per DALY for these services is similar, total benefits are higher for Spring Health water because take-up is higher. For full details, see Burlig et al. (2025).
Policy implications for expanding clean water access
Overall, we believe our research offers strong evidence that decentralised treatment and delivery can overcome long-standing behavioural barriers to clean water access. We also provide some of the first revealed-preference estimates of how much rural households in low-income settings value environmental quality—measured not through how much chlorine they use or how much time they spend finding clean water, but more directly by letting them choose how much to pay for clean water, or conversely how much money to give up in order to obtain it.
References
Ashraf, N, J Berry, and J M Shapiro (2010), “Can higher prices stimulate product use? Evidence from a field experiment in Zambia”, American Economic Review, 100(5): 2383–2413.
Berry, J, G Fischer, and R Guiteras (2020), “Eliciting and utilizing willingness to pay: Evidence from field trials in Northern Ghana”, Journal of Political Economy, 128(4): 1436–1473.
Burlig, F, A Jina, and A Sudarshan (2025), “The value of clean water: Experimental evidence from rural India”, Unpublished manuscript.
Cordoba, C L and J Grabinsky (2020), “Many countries rely on private providers for access to water – but blindly embracing these sources as ‘clean’ raises concerns”, World Bank.
Dupas, P (2024), “Improving access to and usage of clean water”, VoxDev.
Dupas, P, B Nhlema, Z Wagner, A Wolf, and E Wroe (2023), “Expanding access to clean water for the rural poor: Experimental evidence from Malawi”, American Economic Journal: Economic Policy, 15(1): 272–305.
Kremer, M, J Leino, E Miguel, and A P Zwane (2011), “Spring cleaning: Rural water impacts, valuation, and property rights institutions”, Quarterly Journal of Economics, 126(1): 145–205.
Kremer, M, S P Luby, R Maertens, B Tan, and W Więcek (2023), “Water treatment and child mortality: A meta-analysis and cost-effectiveness analysis”, Unpublished manuscript.