Dam Solutions - Water Use

Water is an essential element in everything we consume. It irrigates the plants we use to make the food we eat and the clothes on our backs.

But this water consumption soon adds up. It takes over 200 litres of water to make just one cup of coffee when you take into account the water needed to produce the coffee, milk, sugar, paper cup and lid. A simple cotton t-shirt takes 4,100 litres of water to produce.

And this use is only forecast to increase. Eradicating malnutrition by 2025, with current productivity, requires additional diversions “close to all the water withdrawals at present”.¹

Cotton, rice, and sugar are amongst the thirstiest crops in the world, requiring between 2,000–10,000 litres of water per kg grown.

... and inefficient irrigation

The importance of irrigation in food supply is undeniable: 40% of the world's food is produced from the 17% of land that is irrigated.

But poorly designed irrigation systems and inappropriate field application methods waste a lot of water. Water often evaporates or trickles away before it even reaches the plants!

More sustainable irrigation practices can produce the same amount of food or fibre using less water.

Practices that can reduce water use include:

• Improving management of surface irrigation systems.
• Implementing better field application practices, such as 'bed and furrow' irrigation or drip irrigation.
• Encouraging a cropping pattern adjusted to the local climatic conditions, for instance growing sorghum instead of rice or wheat in drought prone areas.
• Enhancing local water storage in ponds or lakes through small structures, connecting channels, and measures to encourage groundwater recharge, such as the traditional 'tank' system in Southern India.
• Adopting water harvesting techniques.

Daily per capita use of water in residential areas is estimated at 350 litres in North America and Japan and 200 litres in Europe. Meanwhile, people living in sub-Saharan Africa get by on a mere 10-20 litres per person per day.²

As with agriculture, there are substantial savings that can be made in industry and domestic water use.

Supply-side options include:

• Leakage reduction programmes, which stabilise and reduce losses from piped systems.
• Rainwater harvesting through rooftops, tanks, and other methods.
• Infiltration techniques to maintain groundwater levels in areas that have short but intensive rainy seasons.
• Reuse and recycling of water, e.g. implementation of gray water systems.
• Sustainable desalinisation.

Demand-side options include:

• Rights for users to use or trade their water allocations, thus enabling water to be used more productively.
• Realistic pricing to recover the full financial and environmental costs of water.
• Water efficiency standards for industrial and household equipment, such as washing machines.
• Respect for existing legislation and control of water use and protection.
• Education and awareness raising of consumers on water saving practices.