Water Quality
- Created by: Jo Wells
- Created on: 18-04-13 20:28
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- Water Quality
- drinking water needs to be good quality
- must be free of poisonous salts (e.g. nitrates) and harmful microbes
- microbes can cause disease - e.g. cholera and dysentery
- most of our drinking water comes from reservoirs (flows from rivers and groundwater)
- water companies choose to build reservoirs where there's a good supply of clean water
- government agencies keep an eye of pollution in reservoirs
- water goes to water treatment works
- water passes through a mesh screen
- to remove larger things - twigs etc
- chemicals are added, to make solids and microbes stick together and fall to the bottom
- water is filtered through gravel beds to remove all solids
- water is chlorinated to kill off any harmful microbes left
- water is filtered through gravel beds to remove all solids
- some people aren't satisfied & buy filters
- contain carbon/silver to remove substances from their tap water
- carbon removes the chlorine taste
- silver is supposed to kill bugs
- some people in hard water areas buy water softeners (contain ion exchange resins)
- contain carbon/silver to remove substances from their tap water
- totally pure water can be produced by distillation
- boiling water to make steam, then condensing the steam
- process = too expensive to produce tap water
- is used in chemistry labs
- water passes through a mesh screen
- water companies choose to build reservoirs where there's a good supply of clean water
- must be free of poisonous salts (e.g. nitrates) and harmful microbes
- adding fluoride and chlorine has disadvantages
- fluoride is added in some parts of country - helps reduce tooth decay
- chlorine is added to prevent disease
- some studies have linked adding chlorine to an increase in certain cancers
- chlorine can react with other natural substances in water to produce toxic by-products - some think could cause cancer
- in high doses fluoride can cause cancer and bone problems
- also a concern whether it's right to 'mass medicate' - can choose to have fluoride toothpaste, but not if it is in tap water
- levels of chemicals added to water need to be monitored - e.g. some areas may have enough chlorine already
- drinking water needs to be good quality
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