Chlorination Dosing in a Dual Emergency: What WASH Teams Need to Know During the Ebola PHEIC and Ongoing Cholera Burden in DRC and Uganda

On 17 May 2026, WHO declared the Bundibugyo Ebola outbreak in DRC and Uganda a Public Health Emergency of International Concern — the first PHEIC in the Great Lakes region this outbreak cycle. By 25 May, the outbreak had reached 1,018 suspected and confirmed cases and at least 234 deaths, centred in Ituri Province with confirmed cross-border spread into Uganda. At the same time, DRC has recorded more than 64,000 suspected cholera cases since 2025, the country's worst burden in 25 years.

For WASH officers operating in this environment, the practical problem is not unfamiliar: how do you maintain correct free residual chlorine (FRC) across two simultaneous response modes — a drinking water programme targeting cholera prevention and an infection prevention and control (IPC) programme for Ebola — when the chlorine requirements, application concentrations, and supply volumes for each are fundamentally different?

Getting the dosing wrong in either direction has consequences. Under-chlorinated water in a cholera zone extends transmission. Over-concentrated chlorine solutions for hand hygiene in an ETU setting cause skin damage that compromises barrier integrity. With no approved vaccine or therapeutic for the Bundibugyo Ebola strain, containment depends entirely on IPC discipline, which makes reliable chlorine supply and correct dosing more operationally critical than at any other point in the response cycle.

This post sets out the dosing parameters, supply calculations, and procurement considerations that field WASH teams and NGO procurement managers need to navigate this dual-emergency context.

Quick answers for field teams:

• Sphere minimum FRC at point of delivery: 0.2–0.5 mg/L under standard conditions

• Cholera active transmission target: 1.0 mg/L FRC at the source; 0.5 mg/L throughout the distribution chain

• Ebola IPC surface decontamination: 0.5% chlorine solution (5,000 mg/L)

• Ebola hand and skin washing: 0.05% chlorine solution (500 mg/L)

• A standard 45 kg HTH drum at 65% available chlorine treats approximately 585,000 litres to a 1 mg/L dose

Two Responses, Two Chlorine Regimes

The core tension in a dual emergency is that cholera and Ebola require chlorine in fundamentally different forms, concentrations, and volumes.

Cholera prevention is a water treatment function. WASH teams maintain FRC at collection points, standposts, tanker offloading, and household storage. The Sphere Handbook specifies 0.2–0.5 mg/L FRC at the point of delivery. During active transmission, the Global Task Force on Cholera Control recommends raising targets to 1.0 mg/L at the source and 0.5 mg/L at standposts, with 2.0 mg/L in tanker trucks at filling points to account for residual loss during transport. Evidence from the DRC response is striking: after chlorination points were established across Ruzizi health zone, cholera cases fell by 90 percent over eight weeks.

Ebola IPC is a surface decontamination and personal hygiene function. WHO IPC guidelines specify 0.5% chlorine solution (5,000 mg/L) for decontaminating surfaces, equipment, and PPE, and 0.05% (500 mg/L) for handwashing in clinical settings, including ETUs. These concentrations are orders of magnitude higher than drinking water treatment targets, and they are consumed at scale: peer-reviewed data from the Sierra Leone ETU experience published in PLOS ONE documented water consumption of up to 400 litres per bed per day in active ETU operations, almost entirely driven by decontamination demand.

A WASH team managing both functions in the same operational area needs to manage two separate chlorine budgets, two preparation protocols, and two quality-testing regimes — simultaneously.

Calcium Hypochlorite as the Field Standard

Across both response types, HTH Calcium Hypochlorite at 65–70% available chlorine remains the most practical bulk input for field conditions in DRC, Uganda, and the wider East Africa region. Liquid sodium hypochlorite degrades rapidly in heat and cannot be safely stockpiled at field level. Aquatabs (sodium dichloroisocyanurate) tablets are effective for household point-of-use treatment but are not suitable for producing the high-concentration solutions needed for ETU surface decontamination.

HTH granules dissolved in water give field teams direct control over concentration for any application. A single 45 kg drum at 65% available chlorine produces enough 1 mg/L solution to treat approximately 585,000 litres of water — roughly 29,000 person-days at the Sphere minimum of 20 litres per person per day. For decontamination purposes, the same drum produces approximately 900 litres of 0.5% chlorine solution for surface decontamination, or 9,000 litres of 0.05% handwashing solution. Procurement planners can use these ratios to estimate drum requirements against bed capacity and patient throughput.

Shelf life matters in prepositioned stock planning. Properly sealed HTH drums stored in a cool, dry, shaded environment retain potency for 12–18 months from manufacture date. In-country logistics delays are routine in Ituri Province and cross-border routes into Uganda, which means procurement decisions made now — in June 2026 — need to account for stock that may sit in a warehouse or transit hub for weeks before reaching a field site.

For household-level treatment in displacement settings, Aquatabs 67mg remain the appropriate point-of-use option. Each tablet treats 20 litres of clear water to WHO drinking water quality standards, with pre-measured dosing that eliminates preparation error in community use. The distinction between bulk treatment (HTH) and household treatment (Aquatabs) matters for programme design: you are not choosing between them, you are deploying both in parallel, for different points in the water supply chain.

Supply Chain Considerations for Ituri and Cross-Border Routes

The WHO PHEIC declaration on 17 May 2026 triggered accelerated mobilisation by UNICEF, WHO, and implementing partners. But the response is operating under significant constraints. USAID, historically a major procurement partner for WASH supplies, is no longer operational following its disbandment in 2025. Funding pipelines are fragile: UNICEF's 2026 DRC cholera appeal requires approximately $6 million and is described as critically underfunded.

Organisations operating without a prepositioned supply agreement face lead times of four to six weeks for bulk chlorine procurement and delivery into Ituri Province, or into Ugandan response areas near the border. In a fast-moving outbreak, that is too slow. The operational lesson from multiple prior responses is that chlorine must be at the field site before the surge, not ordered in response to it.

The IOM South Sudan Crisis Response Plan 2026 positions Juba as a regional logistics hub with air and road connectivity into DRC and Uganda. For organisations running regional operations, pre-positioning stock in Juba alongside Kampala-based supply gives the fastest possible forward deployment capacity without relying on international air freight.

WASH teams planning procurement should also assess pumping and water distribution equipment requirements in tandem with chlorine supply. ETU sites and cholera treatment centres require continuous clean water supply to operate. Pump failure or inadequate storage capacity is as operationally disabling as chlorine shortfall, and pump procurement often has longer lead times than consumables.

Reading Chlorine Residuals Correctly

One practical field problem that generates a disproportionate share of transmission risk is incorrect FRC testing. Colorimetric DPD test kits are the standard — they are fast, low-cost, and field-deployable. But test results can be invalidated by expired reagents, incorrect sample temperature, or confounding by chloramines in water with high organic load. Teams should establish a testing protocol that specifies: sample collection point, sample temperature range, reagent lot expiry check, and a parallel turbidity assessment.

A high FRC result at the tanker offload point does not confirm safe water at the household storage container. Residual chlorine decays during storage, accelerated by sunlight, heat, and sediment in poorly sealed containers. Evidence-based chlorination research from South Sudan, Jordan, and Rwanda, published in Water Research, found that point-of-use FRC targets need to be calibrated to local storage conditions, not derived from source measurement alone. In practice, this means field teams need to test at the container level, not only at the distribution point.

This is particularly relevant in the Ebola context, where maintaining safe water for handwashing at the household and community transit level is part of the containment strategy, not just a parallel WASH activity.

What This Means for Your Programme

The Bundibugyo Ebola PHEIC in DRC and Uganda is an active procurement signal. WASH officers who wait for programme confirmation before ordering chlorine will be six weeks behind the response curve. The cholera burden in DRC has not subsided — it is concurrent, adding demand to the same supply chain.

Programmes operating in Ituri Province, northern Uganda, or regional hubs supporting cross-border response need chlorine prepositioned at field level before the next patient cohort, not arriving on order. HTH Calcium Hypochlorite for bulk treatment and decontamination, and Aquatabs 67mg for household-level point-of-use treatment, are the two core consumables.

Pump and storage capacity for water distribution infrastructure must be in the supply plan alongside them.

Specialized Logistics Solutions (SLS) holds pre-positioned stock of HTH Calcium Hypochlorite and Aquatabs 67mg in Juba and Kampala, available for rapid dispatch. Contact the team at sales@maji-safi.org.

Frequently Asked Questions

What chlorine concentration should I use for handwashing in an Ebola treatment unit?

WHO IPC guidelines specify 0.05% chlorine solution (500 mg/L) for hand and skin washing in ETU settings. This is produced by dissolving HTH Calcium Hypochlorite granules in water — the precise volume of granules per litre depends on the available chlorine percentage of your stock, so always calculate from your product specification sheet, not from a generic dosing chart.

What FRC level should I maintain during a cholera outbreak?

During active cholera transmission, the Global Task Force on Cholera Control recommends 1.0 mg/L FRC at the source, 0.5 mg/L at standposts, and 2.0 mg/L in tanker trucks at filling points. The Sphere standard minimum (0.2–0.5 mg/L at point of delivery) applies under normal conditions and should be treated as a floor, not a target, during an active outbreak.

Can I use Aquatabs to make decontamination solution for an ETU?

No. Aquatabs 67mg tablets are designed for 20-litre household drinking water treatment at low concentrations. They are not suitable for producing the 0.5% solutions required for surface decontamination or the volume outputs required for ETU operations. HTH Calcium Hypochlorite granules are the correct input for ETU decontamination solutions.

How long does HTH Calcium Hypochlorite last in storage?

Properly sealed HTH drums stored in a cool, dry, shaded environment retain potency for 12–18 months from the manufacture date. Heat and humidity accelerate degradation. Always verify the manufacture date on receipt and rotate stock accordingly — do not assume that drums arriving from a regional hub have a full shelf life remaining.

What is the minimum water quantity per person per day for emergency response?

The Sphere Handbook sets a minimum of 15 litres per person per day for survival needs in acute emergency settings, with 20 litres as the operational planning target. ETU water requirements are far higher — up to 400 litres per bed per day in active operations — driven by decontamination demand. Cholera treatment centres also require substantially more than the household minimum. Programme planners should calculate water demand by facility type, not by applying a single per-capita figure across the response.