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examBoard: Cambridge
examType: IGCSE
lessonTitle: Emergency Water Supplies and Conservation
When natural disasters strike, one of the first and most critical resources to be affected is clean water. Floods can contaminate water sources with sewage and chemicals, earthquakes can rupture water pipes and droughts can deplete available water altogether. Understanding how to secure, purify and conserve water during emergencies is a vital survival skill.
Key Definitions:
Floods: Contaminate water with sewage, chemicals and debris. Water treatment plants may be damaged or overwhelmed.
Earthquakes: Rupture water mains, damage reservoirs and disrupt treatment facilities. Underground aquifers may be altered.
Droughts: Deplete surface water, lower groundwater levels and increase concentration of contaminants in remaining water sources.
The human body requires a minimum of 2-3 litres of water per day for drinking in temperate climates (more in hot weather). Additional water is needed for:
In total, a minimum of 15 litres per person per day is recommended during emergencies.
When normal water supplies are disrupted, communities and individuals must identify alternative sources. These vary depending on the environment and type of disaster.
Most emergency water sources require treatment before they're safe to drink. Multiple methods exist, each with advantages and limitations.
Boiling: Bring water to a rolling boil for at least 1 minute (3 minutes at high altitudes). This kills most pathogens but doesn't remove chemicals or particulates.
SODIS (Solar Disinfection): Fill clear plastic bottles with water and expose to direct sunlight for 6+ hours. UV radiation kills many pathogens. Works best in sunny climates.
Chlorination: Add household bleach (5.25% sodium hypochlorite, unscented) at a ratio of 2 drops per litre. Wait 30 minutes before drinking.
Water purification tablets: Typically contain chlorine, chlorine dioxide, or iodine. Follow package instructions for correct dosage.
Improvised filters: Layered materials (sand, charcoal, cloth) can remove larger particles and some contaminants. Should be combined with disinfection.
Commercial filters: Range from simple ceramic filters to advanced systems. Most remove bacteria and protozoa; fewer remove viruses.
For maximum safety, use multiple methods:
When water supplies are limited, conservation becomes essential. Communities and individuals can significantly extend available supplies through careful management.
When a 6.3 magnitude earthquake struck Christchurch, New Zealand in February 2011, approximately 80% of the city's water supply was disrupted. Damage to underground pipes meant that even where water was flowing, it was potentially contaminated.
Emergency response included:
The city's emergency water management plan helped prevent waterborne disease outbreaks despite significant infrastructure damage. Full restoration of water services took several months, but the emergency measures ensured basic needs were met.
Preparation before disasters occur significantly improves resilience and reduces impacts on water supplies.
In 2019, Chennai, India (population 10 million) faced a severe water crisis when all four of its reservoirs ran dry after a weak monsoon season. This drought-induced emergency highlighted both failures and successes in water management.
Emergency measures included:
The crisis prompted long-term changes including mandatory rainwater harvesting in buildings, restoration of traditional water bodies and improved water conservation awareness among residents.
Building resilient water systems that can withstand natural hazards requires long-term planning and sustainable approaches.
Water security during natural disasters requires preparation, knowledge of emergency sources and purification methods and conservation strategies. By understanding the impacts of different hazards on water systems and implementing appropriate responses, communities can maintain access to this essential resource even when normal infrastructure is compromised.
Remember that water needs vary by climate, activity level and individual health factors. Always prioritize water for drinking and medical needs during emergencies and when in doubt about water safety, treat before consuming. Preparation before disasters occur is the most effective strategy for ensuring water security.
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