It is essential that every community has a clean, constant supply of drinking water.
Large cities are usually supplied with drinking water that comes from surface water sources such as lakes, rivers, and reservoirs.
These sources may be situated nearby or many miles away.
The most important factor is the watershed area from where the water was taken.
This means that in rural areas the water was most likely pumped from a well.
These wells tap into aquifers - the natural reservoirs under the earth's surface - that may be only a few miles wide or may span a huge area.
As with surface water, it is important to remember that activities many miles away from you may affect the quality of ground water.
When water is taken from a river or lake, coagulants are added to remove leaves, twigs and other organic matter.
The water then travels through a filter to remove the smallest contaminants.
Ground water is naturally filtered as it travels through the natural rock formations or aquifers and may not need the above treatment to remove organic matter.
Two other common treatments are the addition of chlorine to disinfect the water in order to remove bacteria and germs and also the addition of activated carbon to adsorb or attract chemicals dissolved in the water.
What are the health effects of contaminants in drinking water? National environmental protection agencies have set standards for many contaminants that may occur in drinking water and pose a risk to human health.
These standards are set to protect the health of everyone, including vulnerable people like the elderly, sick and children.
Contaminants fall into two groups - acute and chronic according to the health effects that they cause.
Acute effects occur within hours or days of the time that a person consumes a contaminant.
People can suffer acute health effects from almost any contaminant if they are exposed to extraordinarily high levels (as in the case of a spill).
In drinking water, microbes, such as bacteria and viruses, are the contaminants with the greatest chance of reaching levels high enough to cause acute health effects.
Most people's bodies can fight off these microbial contaminants the way they fight off germs and these acute contaminants typically do not have permanent effects.
Nevertheless, when high enough levels occur, they can make people ill, and can be dangerous or deadly for a person whose immune system is already weak due to HIV/AIDS, chemotherapy, steroid use or another reason.
Chronic effects occur after people consume a contaminant at levels over the safety standards for many years.
Drinking water contaminants that can have chronic effects are chemicals (such as organic by-products, solvents, and pesticides), radio nuclides (such as radium), minerals (such as arsenic) and heavy metal salts.
Examples of the chronic effects of drinking water contaminants are cancer, liver or kidney problems, or reproductive difficulties.
Other unpredictable factors can have an effect on the quality of our drinking water.
This includes, for example, unusual meteorological conditions which lead to heavy rainfall, the rupture of natural water barriers such as river banks and consequential flooding.
Heavy flooding can cause a breakdown in the sewerage system and contamination of the underlying water table.
There are many benefits to drinking healthy water and nutritional experts say that we should drink at least 7 medium-size glasses of good quality water per day.
The advantage of having a drinking water filter system in your home is that you know that you and your family always have access to the best standard of water in your home and you never have to worry about its quality.
Flooding in the Gloucestershire UK July 2007 The recent floods that have occurred in the county of Gloucestershire in the UK have caused widespread concern amongst local communities.
Residents who have lived in this area confirm that they have seen nothing like it in their lifetimes.
Rivers have burst their banks and the worst hit place is the ancient town of Tewkesbury built where 2 main rivers meet.
Because a main water treatment plant in the town is severely damaged one third of a million (340,000) people in the area are now without running water and are likely to be so for another 2 weeks.
This emphasizes once again the importance of a good clean water supply and the danger that natural catastrophes can bring.