Sizing a growing camp and responding to a diarrhoea outbreak

Today: production (12 + 8) × 12 h = 240 m³/d; after 15% losses: 240 × 0.85 = 204 m³/d; 204,000 / 14,000 = 14.6 L/p/d, just below the Sphere benchmark of 15 L/p/d for drinking and domestic hygiene, on average; some areas are therefore probably well below it.

At 20,000 people, with no change: 204,000 / 20,000 = 10.2 L/p/d. Need: 20,000 × 15 = 300 m³/d distributed, i.e. 300 / 0.85 = 352.9 m³/d of production with current losses: deficit of 112.9 m³/d.

Combination: (1) second generator, 16 hours of pumping: 20 × 16 = 320 m³/d; (2) network repairs, losses down to 5%: 320 × 0.95 = 304 m³/d, i.e. 15.2 L/p/d. Replacing the borehole 1 pump with a 15 m³/h pump would be possible (safe yield), but at 16 hours: (15 + 8) × 16 = 368 m³/d, to be considered only after monitoring water levels and taking the host village's complaint into account. In the meantime, supplementary water trucking targeted at the most remote areas.

Taps (no more than 250 people per tap): 14,000 / 250 = 56, deficit 18; 20,000 / 250 = 80, deficit 42. Also check distance (less than 500 m from each shelter) and queuing time (less than 30 minutes).

Situation: 120 − 22 = 98 usable latrines, i.e. 14,000 / 98 = 143 people per latrine, nearly three times the acute-phase maximum.

Needs (Sphere: no more than 50 people per latrine in the acute phase, 20 in the medium term): today 14,000 / 50 = 280, deficit 182; at 20,000: 400, deficit 302; in the medium term: 20,000 / 20 = 1,000 latrines, or preferably household latrines or latrines shared between a few households.

Priorities: (1) desludge or decommission the 22 full latrines and bring them back into service; (2) phased construction of the 182 missing latrines, starting with the blocks most affected by diarrhoea; (3) sex segregation, lighting, internal locks, safe location, access for persons with disabilities, consultation of women and girls; (4) a handwashing point with soap or chlorinated water at each latrine block: 14 points for 98 latrines is far too few; (5) desludging and faecal sludge management plan, daily cleaning by paid teams or committees.

Interpretation: water leaves the tanks clean (E. coli 0, turbidity below 5 NTU), but chlorination is insufficient for a diarrhoea context: 5 taps out of 12 (41.7%) are below 0.2 mg/L and 2 are contaminated (leaks or recontamination in the network). Sphere aims for 0.2 to 0.5 mg/L at the point of delivery in normal times and a higher level, commonly at least 0.5 mg/L, during an outbreak. In households, 8 containers out of 10 are contaminated with no residual chlorine: contamination occurs after collection (dirty containers, drawing water with hands).

Dose: demand 1.2 mg/L + target residual chlorine 1.0 mg/L = 2.2 mg/L. For 10 m³ = 10,000 L: 10,000 × 2.2 = 22,000 mg = 22 g of active chlorine, i.e. 22 / 0.70 = 31.4 g of HTH per tank. For 240 m³/d: 240,000 × 2.2 = 528,000 mg = 528 g of active chlorine, i.e. 528 / 0.70 = 754 g of HTH per day (about 22.6 kg per month). Contact time of at least 30 minutes, daily testing of residual chlorine at the taps.

Actions: distribution of containers with lids and taps, jerrycan cleaning, chlorination at the point of collection during the outbreak, leak repairs.

Analysis: 12, 19, 41, 77 cases: almost doubling every week (41 to 77, × 1.9); 149 cumulative cases, i.e. an attack rate of 149 / 14,000 = 1.1%. The rapid tests do not confirm cholera but justify a response as for suspected cholera.

Priorities: (1) residual chlorine of at least 0.5 mg/L at all taps, tested twice a day; chlorination at the point of collection; (2) mapping of cases by block with the health team and case-area targeted response around cases (disinfection of latrines and household containers, hygiene kits, information); (3) chlorinated water, handwashing and excreta management in the treatment centre or rehydration unit, with disinfection at exits; (4) rapid increase in available water (second generator, leak repairs); (5) handwashing points at latrines and water points, soap distribution; (6) hygiene promotion by community volunteers on key messages: treated water, handwashing, latrine use, prompt treatment with oral rehydration solution; (7) safe management of dead bodies and funerals, in liaison with the authorities.

Coordination: Ministry of Health, camp health actor, WASH cluster or sector, camp management, and an alert to the host village, which is also exposed.

The complaint must be taken seriously: it may be well founded (drawdown of the water table), and conflict over access to water between refugees and the host community is a risk for protection and for the organisation's acceptance (do no harm principle). I do not take a decision on the basis of opinion alone: (1) measure static and dynamic water levels in borehole 2 and in some village wells for one to two weeks, with the water services; (2) meeting with the chief, the authorities and the camp manager; (3) in the meantime, I do not push borehole 2 beyond its current yield and I shift the increase to borehole 1, whose safe yield is higher. I also propose a tangible benefit for the village: connection of a standpipe, rehabilitation of a well, maintenance jobs. In the medium term: a hydrogeological study and a new borehole away from the village wells. I explain to the camp manager that an increase is still possible, but by another route.