Water demand of a camp, solar and hybrid pumping capacity, flow at the taps

Institutions: consultations 300 × 5 = 1,500 L; inpatients 20 × 50 = 1,000 L; schools 4,200 × 3 = 12,600 L; total 15,100 L = 15.1 m³.

Today: households 12,400 × 15 = 186,000 L; total 186,000 + 15,100 = 201,100 L; with losses × 1.15 = 231,265 L, i.e. 231.3 m³/day.

At 15,000 people: 225,000 + 15,100 = 240,100 L × 1.15 = 276,115 L, i.e. 276.1 m³/day.

Note: 15 L is a minimum; more should be provided as soon as the source allows.

Maximum production: the pump runs 9 hours on solar; that leaves 16 - 9 = 7 hours on the generator, i.e. 7 × 18 = 126 m³. Maximum: 110 + 126 = 236 m³/day (sunny day).

Today: current production 110 + 4 × 18 = 182 m³, insufficient. Generator hours needed: (231.3 - 110) / 18 = 6.74 h (within the 7 h limit). Diesel: 6.74 × 4.5 = 30.3 L/day, about 910 L per month. Cloudy day: 85 + 126 = 211 m³ < 231.3 m³: deficit of 20.3 m³; water available for households = (211 / 1.15 - 15.1) / 12,400 = 13.6 L per person per day.

At 15,000: (276.1 - 110) / 18 = 9.23 h of generator time would be needed, beyond the 7 h possible. Deficit: 276.1 - 236 = 40.1 m³/day. Water available: (236 / 1.15 - 15.1) / 15,000 = 12.7 L per person per day, below the minimum.

Solutions: (1) increase the generator to 6.74 h per day now (7 h on cloudy days) and budget for diesel; (2) reduce losses: leak detection, meters per block (even at 5% losses, 240.1 × 1.05 = 252.1 m³ would remain above 236); (3) a new source before the 15,000 arrive: a second borehole with a pumping test, or extension of the solar array combined with a second borehole; (4) as a temporary and costly solution, water trucking; (5) do not exceed 16 hours, which protects the aquifer and the borehole.

Average flow of the 10 taps: 66.0 / 10 = 6.6 L/min. Two taps in block C (3.1 and 2.9 L/min) are clearly low; without them, the average of the other 8 is 60.0 / 8 = 7.5 L/min.

Capacity of one tap: 7.5 × 60 × 8 = 3,600 L per day, i.e. 3,600 / 15 = 240 people.

Taps needed: today 12,400 / 240 = 51.7, i.e. 52; at 15,000: 15,000 / 240 = 62.5, i.e. 63. There are 42 in service: repair the 6 broken ones (48), then add 4 today and 15 in total within three months, distributed according to the population of each block.

Block C: at the end of the network and at the highest point, the pressure is too low: a tap at 3 L/min serves only about 3 × 480 / 15 = 96 people, hence the 45-minute wait and women coming before dawn (a risk to their safety). Adding taps will not be enough: check for leaks and pipe diameters, install a reinforcement pipe or a buffer tank in block C, rebalance distribution (valves, schedules by block) and consult women on timing and location.

Volume: 600 × 25 + 1,500 × 5 = 15,000 + 7,500 = 22,500 L, i.e. 22.5 m³/day, about 10% of the camp's current demand.

Effect: today, the margin between maximum production (236 m³) and demand (231.3 m³) is only 4.7 m³; at 15,000, the deficit would be 40.1 + 22.5 = 62.6 m³. The borehole cannot supply this water without reducing what refugees receive. Watering livestock at the taps would also be a health risk (contamination) and a source of conflict in the queues.

Response: do not refuse bluntly, because access to water is an issue of peaceful coexistence and tensions already exist. Propose, with the local authorities, camp management and livelihoods actors: (1) rehabilitate a separate source for the village (well, underground tank, borehole) with a livestock trough away from the camp; (2) in the meantime, a limited and supervised solution if production allows (separate trough supplied outside distribution hours, capped volume, after a new source has been commissioned); (3) a joint camp - host community committee to set the rules; (4) include the village in WASH projects (at least one water point for households). Explain the figures to the elders transparently.

Example: "With 12,400 people, demand is 231 m³ per day (15 L per person, institutions and 15% losses). Current pumping (solar and 4 h of generator) produces only 182 m³. I propose moving immediately to 7 h of generator time (about 30 L of diesel per day, 910 L per month). Even so, on cloudy days, households have only 13.6 L per person. At 15,000 people, in three months, the borehole will not be able to supply more than 236 m³ without exceeding 16 h of pumping: a deficit of 40 m³, i.e. 12.7 L per person. Decisions requested: (1) diesel budget; (2) launch of a survey and a second borehole; (3) leak detection and meters per block; (4) 21 taps (6 repairs, 15 new) and reinforcement of the network in block C, where the wait reaches 45 minutes. The neighbouring village's request for 22.5 m³ per day for livestock cannot be met from this borehole: I propose consultation and a separate source."