Ensuring Safe Drinking Water in Disaster-Affected Communities

When disaster strikes-whether it’s a flood, earthquake, cyclone, or conflict-access to clean drinking water often becomes one of the first casualties. Within hours, contaminated water can trigger outbreaks of life-threatening diseases, turning a single crisis into a cascading public health emergency. Understanding how to secure, purify, and distribute safe drinking water in disaster-affected communities isn’t just useful knowledge-it can save lives.

Why safe water becomes critical during disasters 🔗

Disasters disrupt water infrastructure in multiple ways. Water treatment plants may be damaged, pipes can break and mix with sewage, and floodwaters routinely contaminate wells and boreholes with faecal matter from overflowing latrines and sewers. According to the World Health Organization, during emergencies, it should be assumed that all water is at risk of contamination-including piped supplies-until authorities confirm otherwise.

The consequences of drinking contaminated water can be swift and deadly. Waterborne diseases such as cholera, typhoid fever, dysentery, and hepatitis A spread rapidly through contaminated water supplies. These diseases are particularly dangerous in disaster settings where healthcare systems may be overwhelmed or destroyed. The UN Office for Disaster Risk Reduction notes that microbiologically contaminated drinking water causes approximately 505,000 diarrhoeal deaths annually worldwide-with the risk significantly higher in disaster-affected areas.

Who faces the greatest risk? 🔗

Children under five years old and the elderly are the most vulnerable to waterborne illnesses. Research published in the National Institutes of Health indicates that about 90% of deaths due to diarrhoea occur in children under five. Pregnant and breastfeeding women also face heightened risks, as dehydration and infection can have severe consequences for both mother and child.

Recent disasters have demonstrated these risks clearly. Following the 2022 Pakistan floods, the British Red Cross reported that over 90,000 cases of diarrhoea were recorded in Sindh province in a single day, with hundreds of thousands affected by acute watery diarrhoea, skin infections, and typhoid.

Water purification methods for emergency settings 🔗

When safe water cannot be supplied through normal channels, treating water at the household or community level becomes essential. Several proven methods can make contaminated water safe for drinking, each with specific advantages depending on available resources.

Boiling: the most reliable method 🔗

Boiling remains the most effective way to kill disease-causing organisms in water. The Centers for Disease Control and Prevention recommends bringing clear water to a rolling boil for at least one minute-or three minutes at elevations above 6,500 feet. If water appears cloudy, it should first be filtered through a clean cloth, paper towel, or coffee filter to remove visible particles.

After boiling, water should be allowed to cool naturally and stored in clean, sanitised containers with tight-fitting lids. While boiling is highly effective, it does require fuel, which may be scarce in disaster zones.

Chemical disinfection 🔗

When boiling isn’t practical, chemical disinfection offers a reliable alternative. Chlorine-based disinfectants-including unscented household bleach, chlorine tablets, or chlorine dioxide tablets-can kill most bacteria and viruses in water.

For household bleach containing 5-9% sodium hypochlorite, the CDC recommends adding 8 drops per gallon of clear water, stirring well, and allowing the water to stand for at least 30 minutes before drinking. If water is cloudy or very cold, the amount should be doubled.

One limitation of chemical disinfection is that standard chlorine and iodine treatments may not effectively kill certain parasites, particularly Cryptosporidium and Giardia. For areas where these parasites are a concern, chlorine dioxide tablets are more effective.

Solar disinfection (SODIS) 🔗

In situations where neither fuel nor chemical disinfectants are available, solar disinfection provides a zero-cost alternative. This technique involves filling clear plastic bottles with water and placing them in direct sunlight for at least six hours on sunny days or two days under cloudy conditions. The WHO notes that empty bottles left over from initial water shipments can be repurposed for this method.

UV rays from sunlight inactivate most pathogens, though the method works best with clear water. Cloudy water should be filtered or allowed to settle first, as particles can shield microorganisms from the sun’s rays.

Sedimentation and filtration 🔗

Before applying any disinfection method, heavily contaminated water benefits from sedimentation-simply allowing particles to settle to the bottom-followed by careful decanting of the clearer water above. Passing water through clean cloth, sand filters, or ceramic pot filters removes suspended particles and some pathogens.

However, filtration alone doesn’t guarantee safety. Portable filters must have absolute pore sizes of 1 micron or smaller to remove parasites and 0.3 microns or smaller to remove bacteria. Even then, filters cannot remove viruses, so filtered water should still be chemically disinfected.

Water storage and distribution in disaster zones 🔗

Purifying water solves only part of the problem. Equally important is storing treated water safely and distributing it efficiently to affected populations.

Safe storage practices 🔗

Treated water can easily become recontaminated if stored improperly. The CDC recommends using food-grade containers with tight-fitting lids that can be sealed completely. Containers should be sanitised before use with a dilute bleach solution.

Key storage guidelines include keeping containers away from direct sunlight, maintaining cool temperatures between 50-70°F where possible, labelling containers with the storage date, and replacing stored water every six months. When retrieving water, clean utensils should be used rather than hands, which can introduce contamination.

For larger-scale storage, emergency response organisations deploy various solutions including collapsible bladder tanks, rigid polyethylene tanks, and steel frame tanks with liners. According to humanitarian relief specialists, a 10,000-litre portable tank can provide water for up to 650 people daily when distributed at the WHO-recommended minimum of 15 litres per person.

Distribution systems 🔗

Getting water from storage points to affected populations requires coordinated logistics. In immediate post-disaster situations, bottled water may be distributed directly, though this approach is expensive and generates significant plastic waste.

More sustainable options include water tanker trucks delivering to central distribution points, portable tap stands connected to storage bladders, and mobile water distribution units that can fill reusable containers. The WHO emphasises that a minimum of 7.5 litres per person per day is needed for survival in the immediate aftermath, increasing to 15 litres as soon as possible, and ideally 20 litres per day to cover basic hygiene and food preparation needs.

Local authorities typically coordinate distribution efforts, establishing collection points at accessible locations while ensuring vulnerable populations-including the elderly, disabled, and those caring for young children-aren’t disadvantaged by distribution arrangements.

Maintaining water quality during distribution 🔗

Water quality must be maintained throughout the distribution chain. The WHO recommends maintaining a free chlorine residual of at least 0.5 mg/litre in distribution systems during emergencies to prevent secondary contamination from damaged infrastructure or handling.

Storage tanks and tanker trucks require regular cleaning and disinfection. This involves draining, scrubbing interior surfaces, disinfecting with chlorine solution, and thorough rinsing before refilling. Distribution points should be kept clean, with spillage managed to prevent standing water that could breed mosquitoes.

Beyond water: the broader WASH response 🔗

Safe water is inseparable from sanitation and hygiene-the three elements of what disaster responders call WASH. Providing clean water has limited impact if people lack sanitation facilities or don’t practise proper handwashing.

Emergency sanitation might range from designated defecation fields in the immediate aftermath to trench latrines and eventually more permanent pit latrines. These facilities should be positioned at least 50 metres from water sources and located downhill and downstream from water collection points.

Handwashing with soap at critical times-after defecation, after handling children’s faeces, and before preparing or eating food-is among the most effective disease prevention measures. When soap is unavailable, ash, sand, or other locally available substitutes can be promoted as alternatives.

Preparing communities before disaster strikes 🔗

The most effective disaster response begins before any emergency occurs. Households in disaster-prone areas should maintain emergency water supplies-at least one gallon per person per day for a minimum of three days, ideally longer. Water storage containers should be checked and rotated regularly.

Community-level preparedness includes mapping water sources, training residents in household water treatment methods, pre-positioning emergency supplies, and establishing clear communication channels for alerting populations when water supplies may be compromised.

Water utilities and local authorities can strengthen resilience by maintaining infrastructure, developing emergency response plans, and participating in regional mutual aid networks that allow utilities to share resources during crises.

What do you think? How prepared is your community for a water emergency, and what steps could you take today to improve your household’s water security in a disaster situation?

References

1. https://www.who.int/teams/environment-climate-change-and-health/water-sanitation-and-health/environmental-health-in-emergencies/humanitarian-emergencies
2. https://www.undrr.org/understanding-disaster-risk/terminology/hips/bi0110
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC7150208/
4. https://www.redcross.org.uk/stories/disasters-and-emergencies/world/risk-of-waterborne-disease-after-pakistan-floods
5. https://www.cdc.gov/water-emergency/about/index.html
6. https://www.cdc.gov/water-emergency/about/how-to-create-and-store-an-emergency-water-supply.html
7. https://fastank.com/emergency-water-storage/