Water » Sustainable Water Supplies

Moving towards a sustainable water future

Big projects such as dams and water transfers can add a lot of water, but they are expensive and can harm the environment. A more sustainable approach looks after water so that people today can use it without running it out for people in the future.

Sustainable water supply is about two things: using less water, and making better use of the water we already have. The spec names four ideas: water conservation, groundwater management, recycling and grey water.

Key terms:

• Water conservation: using water carefully and reducing the amount that is wasted.
• Groundwater management: controlling how much water is taken from underground stores, and helping those stores to refill.
• Recycling (water): cleaning used water so that it can be used again.
• Grey water: waste water from baths, showers, sinks and washing machines. It is not toilet waste, so it is only lightly dirty.

Water conservation

Conservation means every person, farm and factory uses less. It is often the cheapest way to make water supplies last longer, because no new water has to be found.

Conservation also means stopping leaks in pipes. In some places a lot of water is lost underground before it ever reaches a tap. Repairing old pipes saves water at no cost to the environment.

Conservation works best when people understand why it matters. That is why schemes often include education about saving water.

Groundwater management

Groundwater is a valuable store, but it can be used faster than it refills. Groundwater management tries to keep the store healthy. It can include:

• limiting how much water farms and industries are allowed to take out;
• checking how high the water level underground is, so problems are spotted early;
• helping rain to soak into the ground so that the store is topped up (this is called recharge);
• keeping pollution away from the ground above the store.

If groundwater is managed well, wells and springs keep working and the supply lasts for the long term.

Recycling and grey water

Most water is used once and then thrown away. Recycling gives it a second life.

A local scheme in an LIC or NEE: the Wakel River Basin, Rajasthan, India

India is a newly emerging economy (NEE). Rajasthan is a state in the north west of India, and it is one of the driest parts of the country. The Wakel River Basin is in the south of Rajasthan.

The problem

• The area is very dry. Less than 250 mm of rain falls in a year, almost all of it in the monsoon between June and September.
• Summer temperatures can reach 53°C, so water evaporates quickly.
• Over-irrigation and taking too much water from wells had lowered the water table. Some wells had dried up.

The scheme

An NGO worked with local communities, with money from the US government's aid agency (USAID). The aim was to harvest the monsoon rain and use it carefully. The scheme used traditional methods:

Local people were taught about saving and managing water, and they helped to decide how it should be shared.

Why is it sustainable?

• Social: local people are involved, so they can look after the structures themselves.
• Economic: the structures are cheap and are built using local skills and materials, so they are affordable for a poor area.
• Environmental: groundwater is refilled rather than used up, and the water comes from local monsoon rain.

Compare this with a large scheme: it is small, local and low technology. It does not give huge amounts of water, but it is cheap and long lasting.

Exam-style question

(a) What is meant by grey water? [1 mark]

(b) Explain one way groundwater can be managed more sustainably. [2 marks]

(c) For a named local scheme in an LIC or NEE, explain how it has increased sustainable water supplies. [4 marks]