Emergency Water Storage for Cholera Response: Bladder Tanks

In early 2026, the Democratic Republic of Congo recorded its worst cholera outbreak in 25 years — more than 64,000 cases and 1,800 deaths, with 17 of 26 provinces affected. At the same time, UNICEF confirmed active cholera transmission across 12 countries in West and Central Africa, with 80,000 children at heightened risk as the rainy season began. For WASH coordinators mobilising into these environments, the immediate question is rarely which water purification tablet to procure. It is this: where will the water be safely stored once it has been treated? Emergency bladder tank water storage is the infrastructure that makes every other WASH intervention function, and getting it right from the start is the difference between a cholera response and a cholera amplification event.

Why Water Storage Is the First Priority in Cholera Response

Cholera spreads primarily through water contaminated with the Vibrio cholerae bacterium, and one of the most dangerous transmission points in a humanitarian setting is not the source — it is the storage container. Water that has been treated at the point of collection can be recontaminated during transport or home storage if containers are inadequately sealed, accessed by hand, or left open. In a displacement camp or conflict-affected urban area, the chain of custody from treatment point to point of use must be protected at every stage.

This is why closed, food-grade bladder tanks are a cornerstone of cholera response infrastructure. Unlike open steel tanks or jerry cans, bladder tanks provide a sealed, chlorine-compatible storage environment that protects treated water from environmental and human contamination. When positioned correctly — elevated approximately 1.5 metres above tapstand level for gravity feed — they eliminate the risk of recontamination during water collection, one of the highest-risk moments in any camp water system.

The Sphere Handbook sets a minimum of 15 litres of safe water per person per day in emergency settings, rising to 20 litres once the response stabilises. Meeting this standard requires not just the right treatment products but the right storage capacity to buffer supply against interruptions in pumping, trucking, or treatment. In eastern DRC — where a humanitarian access agreement between the DRC government and AFC/M23 was signed on 18 April 2026, opening new corridors for aid delivery — teams re-entering after months of restricted access will need to establish storage infrastructure rapidly to support cholera-affected populations.

Oxfam Bladder Tanks and Butyl Products Flexitanks: Choosing the Right System

We supply two distinct product lines for emergency water storage, and the choice between them depends on operational context, deployment duration, and terrain. The Oxfam bladder tank is a closed PVC-coated polyester tank manufactured from UV-resistant, food-grade material with heat-welded seams. It is fitted with a 2-inch BSP outlet and a screwed filler cap inlet, and each unit ships with a groundsheet for surface protection and basic valve fittings. Oxfam tanks are suited for rapid deployment in accessible field locations — lightweight, compact when flat, and operational within hours of arrival.

Butyl Products bladder tanks, which we distribute as an authorised partner, are constructed from vulcanised natural rubber — a significantly more durable material suited to longer operational deployments, rough terrain, and environments where UV degradation or puncture risk is a concern. Where an Oxfam tank is the right tool for a three-month cholera response, a Butyl Products tank is the right tool for a semi-permanent field base or a location where replacing a damaged unit is logistically difficult. Both product lines are available in multiple capacities, allowing WASH teams to match storage volume precisely to population size.

For WASH coordinators assessing which system to specify, the key variables are: expected deployment duration (shorter favours Oxfam PVC; longer favours Butyl rubber), surface conditions at the site, and supply chain access for replacement units if the primary tank is damaged. Both systems are fully compatible with chlorinated potable water. You can review our full range of storage and treatment products on our WASH products page.

Sizing and Positioning Water Storage for Camp and IDP Site Operations

Sizing is where many field WASH plans fall short in the early days of a response. The starting calculation is straightforward: multiply the population by 20 litres per person per day to get the daily water requirement, then plan for at least one day of buffer storage — ideally two — to account for delays in trucking or treatment. A camp of 5,000 people requires 100,000 litres of daily supply. To hold two days of buffer, you need 200,000 litres of storage capacity — roughly 20 units of a 10,000-litre bladder tank, or four units of a 50,000-litre tank.

Positioning matters as much as sizing. Bladder tanks must be sited on reasonably level ground to prevent rolling when full. A groundsheet should be placed beneath the tank before filling. The outlet must be elevated approximately 1.5 metres above the tapstand to allow gravity feed without pumping, which simplifies operations and eliminates a contamination point at the distribution point. For sites where elevation is not possible, a low-pressure pump can be used to transfer water from a ground-level tank to distribution points — our pump equipment range includes transfer pumps suited exactly to this application.

Minimum separation distances should also be observed: bladder tanks should be located no less than 30 metres from latrine blocks and not downhill from any waste disposal or defecation area. In conflict-affected settings where space is constrained — as is the case in many displacement sites in eastern DRC or South Sudan — careful site planning at the start of a response saves significant time and risk later.

Maintaining Water Quality: Chlorine Residual in Stored Water

A bladder tank that holds treated water is only as safe as the chlorine residual maintained within it. WHO and Sphere guidance calls for a minimum free residual chlorine of 0.5 mg/L at the point of delivery to consumers, with treated water in storage protected against recontamination for between 4 and 24 hours. In hot climates — which describes virtually all of SLS's operational regions — chlorine degrades faster, meaning that water stored in direct sunlight in an improperly shaded tank can lose its protective residual before it is distributed.

This has two practical implications. First, bladder tanks should be shaded where possible — a simple tarpaulin frame is sufficient — and should not be sited in direct, unbroken sunlight in locations with ambient temperatures above 35 degrees Celsius.

Second, chlorine residual must be tested at the tapstand, not only at the treatment point. We supply chlorination equipment and dosing systems as part of our WASH product range, including the consumables and test kits needed to maintain residual monitoring through the full distribution chain.

Tank hygiene is equally important. Bladder tanks used in cholera response should be cleaned and disinfected between fill cycles wherever possible, and outlets and filling caps should be inspected regularly for damage or contamination. A cracked fitting that allows ambient water ingress can undermine an otherwise well-managed water supply system within hours.

As cholera continues to spread across Central and West Africa, and as humanitarian access to conflict-affected areas opens and closes with unpredictable speed, pre-positioned water storage capacity is one of the most important variables a WASH team can control. We stock Oxfam bladder tanks and Butyl Products flexitanks in Juba and Kampala for rapid dispatch across East and Central Africa. If you are planning a cholera response or pre-positioning supplies for the 2026 rainy season, contact SLS to discuss your requirements.