In the UK, we take it for granted that we turn the tap on and clean, safe drinking water comes through the tap. However, with increasing demand upon water supplies and long dry periods, is water really as ‘renewable’ as we think?
Water levels in the UK are determined by rainfall. On average rainfall in the UK has fallen over the last few years meaning water levels in some parts of the country are very low. Geographically the driest places in the UK are also the areas which have the highest population density, meaning meeting water demand for domestic application alone can be very challenging.
Current aquifer and reservoir levels for water suppliers (for whom data is available) in the UK are shown below. Southern and South East Water who supply to East Anglia and the surrounding areas clearly show how reserve levels are very low in these dry and high demand areas.
Great Britain is leaking. This is mainly due to the age of the infrastructure in place and the massive task both logistically and financially to retrofit the entire system. Following the droughts experienced in 1993, targets were set each year for water companies to improve distribution pipes to reduce water wastage through leaks.
So how much water do we use each day? For domestic use, like cooking and cleaning, bathing and watering the garden, each one of us uses around 152 litres a day. For a family of four, that’s 18240 litres a month! So if you put together the water that the average sized housing estate uses (170 families) they would be using a 25m swimming pool’s worth of water each month.
Water, by its very nature, can become polluted quite easily and this pollution can have a huge impact across a large geographical area. If pollution is caused at one part of the water course (such as an oil spill), this is called ‘point source pollution’, pollution that is spread over a large area is called ‘trans-boundary pollution.’
There are specific types of pollution which affect different parts of the water cycle. Ground Water pollution: Affects water in wells, bore holes and aquifers and is often caused by pesticides used in agriculture.
Micro-organisms are naturally occurring but can be a huge problem to both people and animals if water treatment is not available. Oxygen depletion can cause the development of harmful anaerobic micro-organisms which form when the increase of organic material is degraded by microbes using up the oxygen in the water.
Oxygen depletion can also be caused by an increase in nutrient levels caused by fertiliser and waste water run-offs, these encourage algae growth which use up the oxygen in the water suffocating other marine life. This increase in nutrient level is called eutrophication.
Chemicals often find their way into our water system from industrial and agricultural processes. Pesticides used to kill weeds, insects and fungi can poison marine life and continue up the food chain to humans and animals who eat infected fish. Marine life can also suffer improper development and infertility from metal and solvents contaminating water from industrial processes.
One of the most well known forms of water pollution is from petroleum products or oil spills. These are caused by ships leaking oil and, although localised to a point, oil slicks can spread quickly and devastate marine life for hundreds of miles.
Where does pollution come from? Domestic, agricultural and industrial processes all cause water pollution. Waste water containing sewage has to be treated and allowed to degrade into safe materials before the water can be released back into the watercourse. If this treatment doesn’t happen then harmful bacteria and viruses can poison the environment.
Factories and industry use water to take away waste products from processes and to wash down work areas, this can lead to contamination of ecosystems.
People leaving litter near rivers and water systems or dumping litter and waste into rivers and oceans also causes pollution; it can take hundreds of years for some waste to degrade.
Water pollution can also be caused by chemical compounds in the air reacting with water vapour in clouds, these clouds then lose the contaminated vapour through rain where it enters the watercourse.