Reducing Rainfall-Related Disease in Rural Sub-Saharan Africa by Adjusting Water Price with 'Water ATMs' During Periods of Rainfall, Providing a Dynamic Health Intervention to Climate Variability

Across much of rural sub-Saharan Africa households have been shown to change water collection during periods of rainfall away from cleaner groundwater sources towards free alternative sources like surface water. This often substantially increases disease risk and decreases service sustainability. Incentivising households to maintain collection of clean groundwater could mitigate this challenge and improve community health. 'Water ATMs' are increasingly installed in rural piped systems, and remotely monitor volumetric use and facilitate pre-payment, now allowing for precise and accountable pricing interventions. We propose and investigate the potential of a novel pricing mechanism predicated on reducing water price at water ATMs during rainfall periods.

We calculate suitable price reductions derived from measured reductions in water collection of -20% to -30% over rainfall periods from seven countries, as determined from satellite-based records and literature. We apply these to different scenarios based on real communities, and likely scenarios, in Tanzania and The Gambia, over ranges of price elasticity (-0.5 to -1) and relative risks of diarrhoeal disease from this intervention (0.4 to 0.8), both determined from representative studies. Annual costs per capita and costs per DALY (disability-adjusted life year) averted from such an intervention are estimated.

Between 5 and 50 USD per DALY averted are estimated for these scenarios. Such costs would compare favourably against those reported for other water quality interventions. Exact cost and value depend on community response to lower prices and specific disease reductions from maintained use of cleaner water. Pricing and length of intervention could be adjusted depending on community setting to minimise cost per DALY averted. This science-based strategy has potential to cheaply mitigate the disease risk that comes with rainfall. Piggy-backing on existing water ATM projects eliminates further capital expenditure. Implementation will require understanding community behaviour and context. Subsidising costs may provide a new avenue for accurate subsidy transfers to service providers for precise lost revenues, and its flexibility to variable rainfall may buffer the water-health impacts of climate change; both desirable to policymakers.