Handwashing Station Water Budgets for Schools Without Piped Water: Dispenser Volume, Break-Time Throughput, Soap and Haul

SIMULATED, NOT MEASURED. A water-budget design method for handwashing in schools without piped water. For a target of 3 effective washes per pupil per day within 1.0 L per pupil per day, only a tippy-tap class dispenser (0.20 L per wash) fits the budget at 0.69 L per pupil per day, requiring 6 stations per 100 pupils, 207.0 L hauled daily for 300 pupils and 93.6 kg soap per year, at US$3.22 per child per year excluding water and haul labour. Failure cases for play/waste, too few stations and absent soap are stated in full. Nothing was built and no water was used by children.