Water security and equity

· Water security = access to sufficient amounts of safe drinking water; it is essential for sustainable societies.
· Freshwater access is shaped by social, cultural, economic and political factors, not just rainfall or river supply.
· Equitable access means people can obtain safe, affordable, reliable water and sanitation, regardless of income, identity, location or political power.
· Exam links: connect water access to sustainable development, environmental justice, human well-being, health, education and poverty reduction.
· Strong answers distinguish between water availability and water accessibility: water may exist in a region but be unavailable because of poor infrastructure, cost, conflict or pollution.

This infographic summarises why water security is broader than simply having water present. It links water access to health, livelihoods, development, ecosystems and stability, which are all useful for ESS exam explanations. Source

Water use and rising demand

· Human societies with population growth or economic development must increase water supply or improve efficiency of water use.
· Main human uses: domestic use, agricultural irrigation, livestock, and industry.
· Agriculture is often the largest water-demand sector because irrigation and livestock production require large volumes of freshwater.
· Economic development can increase demand through industry, urbanization, energy production, higher consumption and more water-intensive diets.
· In exams, explain rising demand as a systems issue: more people + higher consumption + limited freshwater + uneven access = increasing water insecurity.

This diagram is useful for showing water use as a system with sources, treatment, transmission, storage, distribution and withdrawals. It helps students explain how infrastructure affects access to usable freshwater. Source

Water scarcity: physical vs economic

· Water scarcity = limited availability of water for human societies.
· Physical water scarcity = water is naturally or actually limited because demand exceeds available supply.
· Economic water scarcity = water may be present, but people lack infrastructure, storage, transport, finance or governance to access it safely.
· Water stress is broader than scarcity because it also considers water quality, environmental flows and accessibility.
· Water stress threshold: clean, accessible water supply of less than 1,700 m³ per person per year.
· A region can have water but still suffer water stress if the water is polluted, unaffordable, unreliable or needed to maintain ecosystems.

Increasing water supply

· Water supplies can be increased using dams, reservoirs, rainwater catchment systems, desalination plants and enhancement of natural wetlands.
· Dams and reservoirs store water for dry periods, irrigation, domestic supply and sometimes hydropower, but may flood habitats and displace communities.
· Rainwater harvesting captures precipitation for later use and can reduce pressure on mains supply or groundwater.
· Desalination removes salt and minerals from seawater or brackish water to produce freshwater.
· Reverse osmosis = desalination method where pressure forces water through a semi-permeable membrane, leaving salts behind.
· Wetland enhancement can improve natural storage, filtration and flood regulation while supporting biodiversity.
· Evaluation point: increasing supply can improve water security, but often has economic costs, energy demands, ecosystem impacts and equity issues.

This diagram shows how rainwater can be collected, filtered and stored for household use. It is a clear example of a local-scale strategy for increasing usable water supply. Source

This diagram helps explain why reverse osmosis is used in desalination. Pressure is applied to push water through a membrane while dissolved salts are left behind, producing freshwater but requiring energy. Source

Domestic water conservation

· Water conservation reduces demand and improves water security without always needing new supply infrastructure.
· Domestic techniques include metering, rationing, grey-water recycling, low-flush toilets and rainwater harvesting.
· Metering encourages users to reduce consumption because use is measured and often charged.
· Rationing can reduce demand during drought but may create social tensions if access is unequal.
· Grey-water recycling reuses water from sinks, showers or laundry for uses such as toilet flushing or irrigation.
· Low-flush toilets reduce household water demand because toilets are a major indoor water-use category.

Industrial and food-production water conservation

· Industrial and food-production strategies include greenhouses using recycled harvested rainwater, aquaponics, drip irrigation, drought-resistant crops and switching to vegetarian food production.
· Drip irrigation applies water directly to plant roots, reducing evaporation and run-off compared with flood or spray irrigation.
· Aquaponics combines fish production with plant production so nutrient-rich water can be reused.
· Drought-resistant crops reduce crop failure and irrigation demand in dry or variable climates.
· Vegetarian food production usually reduces water demand because eating lower on the food chain often requires fewer water-intensive inputs than livestock systems.

Mitigation strategies for water scarcity

· Mitigation strategies aim to reduce the causes or impacts of water scarcity and water stress.
· Suitable strategies depend on the named country, its climate, wealth, technology, governance, population pressure and development priorities.
· Possible strategies: dams, water transfers, pipelines, tankers, estuary storage with barrages, cloud seeding, desalination, solar distillation, dew harvesting, water treatment plants, aquifer storage and recovery (ASR) and artificial recharge of aquifers (AR).
· Strong evaluation compares benefits and limits: cost, energy use, reliability, ecosystem damage, carbon emissions, equity, maintenance and long-term sustainability.
· Named-country answers should include specific strategy + reason for water stress + benefit + limitation.

Environmental impacts of industrial freshwater production

· Industrial freshwater production can improve water security but has negative environmental impacts that can be minimized but not usually eliminated.
· Desalination impacts include concentrated brine discharge, which can increase salinity and harm marine ecosystems near outfalls.
· Other impacts: noise, air pollution, energy demand, greenhouse gas emissions, and damage linked to fossil-fuel combustion.
· Groundwater abstraction may cause aquifer depletion, land subsidence or saline intrusion in coastal aquifers.
· Evaluation point: desalination is useful where countries have coastlines and capital, but it is less sustainable if powered by fossil fuels or poorly managed brine disposal.