We are used to think of England as a wet country, and all the rain falling at neat interval helps drive a natural obsession with the weather. We take water for granted. We make the assumption that there is plenty of it, and that it is cheap and affordable. It is difficult to make the connection between the water we use every day the health of our rivers [similarly to making the connection between our energy use and the impact on the environment].
The truth is slightly different. There are parts of England that have less rainfall per person than some Mediterranean countries. The dry spring of 2011, the drought in South East England in 2004-06, and the floods of 2007 have showed how quickly changes in rainfall can affect rivers and reduce what we take from them to water crops and supply homes and businesses.
Water supplies are at present under stress in some parts of England. Because of over-abstraction [meaning that we abstract more water than it will naturally be possible to replenish] only a quarter of UK rivers and lakes are fully functioning ecosystems. The combined effects of a growing population and climate change and are likely to put increasing pressure on rivers, lakes and aquifers in the coming years. If we do not act, the security of the water supplies could be compromised.
Clean, flourishing water bodies are an essential part of the natural environment, giving life to animals, plants, and people. Water is also integral to the economy. We need it to grow food, for industrial processes and for energy production. We need water to supply our homes and businesses, however we are taking too much water from our rivers and the groundwater that feeds them, damaging natural ecosystems. As the water flow in rivers reduces, the health of the water environment deteriorates because there is less water to dilute pollution and to support fish and other wildlife. As we look to the future, we can expect climate change to reduce the amount of water in our rivers, at the same time as a growing population drive up demand. If we fail to take this challenge seriously we not only risk irreparable damage to our environment, we threaten our economy.
Water demand in the UK
Households water demand has been increasing since the 1950s, due to population growth and changes in the patterns of water use in the home, while water use by industry has been declining with the relocation of heavy industry. As a result, households now use more or less half of the water put into the public supply.
It is estimated that the average water use in England is around 150 litres per person per day, equivalent to approximately one tonne of water per week. International comparisons are not always straightforward, but it seems many other countries are already using substantially less than this, although UK is already doing better compared to other countries. However there is plenty of space for improvements.
Water companies predict that average personal consumption will decrease from 154 litres per day in 2010-11 to 144 litres in 2030-31. The growing population will however offset this reduction, with total househol demand expected to rise. In southern and eastern regions of England, where rainfall is comparatively low, per capita water consumption tends to be higher than elsewhere. In some areas abstraction is above its sustainable level.
The impacts of climate change
The predictions are that over time average temperature will increase due to climate change, but the effects on rainfall are less easy to predict. The UKCP09 [UK Climate Projections 2009] indicates that on average the UK will experience warming temperature and changes in seasonal precipitation patterns, while extreme weather events will be more common and more intense.
This will have an impact on water resource. Hotter weather would likely lead to more evaporation from reservoirs and rivers, while acquifers will not be recharged as efficiently by the more intense rainfall expected [the runoff effect]. Intense rainfall would also lead to surface flooding, more pollutants being diluted into rivers, and would also affect coastal waters. While there are still some degrees of uncertainity around future precipitation, current projections suggest on average less rainfall in summer. As a result, rivers are likely to see lower flows in summer, though the effects in other seasons are much more difficult to predict.
Climate change is likely to affect also future demand. We tend to use more water in warmer weather, for example for washing and drinking, or to water gardens. Other effects are harder to predict, for instance whether farmers choose to irrigate more or change the crops they grow. The level of water demand may also change at some power stations because of the drive to reduce carbon emissions.
The water industry today emits under 1% of total UK greenhouse gas emissions, primarily due to treating and supplying water and disposing of wastewater, but there is the risk that this measure will rise with water demand and more ambitious standards for water quality. The water industry must therefore play its full part in meeting national targets for the reduction of greenhouse gas emissions and explore its significant potential for renewable energy generation and use.
In addition to the emissions by the water industry, hot water use in our homes is responsible for 35 million tonnes of greenhouse gas emissions each year: over 5% of total UK greenhouse gas emissions. Water efficiency measures, particularly those that focus on hot water use, are therefore doubly beneficial, with water as well as greenhouse gas savings.
DEFRA (2011). Water for life. Presented to Parliament by the Secretary of State for Environment, Food and Rural Affairs by Command of Her Majesty. London, DEFRA.
DEFRA (2008). Future Water. The Government’s water strategy for England Presented to Parliament by the Secretary of State for Environment, Food and Rural Affairs by Command of Her Majesty. London, DEFRA.