Water quality Flashcards
What does drinking water need to be?
Good quality.
What is water essential for?
Life.
What must water be free f?
- Poisonous salts (e.g.phosphates and nitrates).
- Harmful microbes.
Why does water need to be free of harmful microbes?
As microbes in water can cause diseases such as cholera and dysentery.
Where does most of our drinking water come from?
Reservoirs.
How does water get into reservoirs?
It flows from rivers and groundwater.
What do watercompanies choose to do?
Build reservoirs where theree’s a good supply of clean water.
What do government agencies do?
Keep a close eye on pollution in reservoirs, rivers and groundwater.
How do we make water of a good quality?
Water from reservoirs goes to the water treatment works for treatment.
How do the water treatment works work?
- The water passes through a mesh screen to remove big bits like twigs.
- Chemicals are added to make solids and microbes stuck together and fall to the bottom.
- The water is filtered through gravel beds to remove all the solids.
- Water is chlorinated to kill off any harmful microbes left.
What are some people not with the water treatment process.
Not satisfied.
What do the people who are unsatisfied about the water treatment process do?
They buy filters that contain carbon or silver to remove substances from their tap water.
What do the filters do that are bought by people who are unsatisfied with the water treatment process?
- The carbon in the filters removes chlorine taste.
- The silver in the filters is supposed to kill bugs.
What do people in hard water areas buy?
Water softeners which contain ion exchange resins.
What is totally pure water?
Water with nothing dissolved in it.
How can totally pure water be produced?
By distillation.
How do we produce totally pure water through distillation?
- By boiling water to make steam.
- Then condensing the steam.
Why don’t we use the distilling process to produce totally pure water in tap water?
Because this process is too expensive, because lots of energy would be needed to boil all he water we use.
Where is distilled water used in?
Chemistry labs.
What is added to drinking water?
- Fluoride (in some parts of the country).
- Chloride.
Why is fluoride added to drinking water?
Because it helps to reduce tooth decay.
Why is chlorine added to drinking water?
To prevent disease.
What does adding fluoride and chlorine to water have?
Disadvantages as well as advantages.
What are the disadvantages of adding chlorine to drinking water?
- Some studies have linked this with an increase in certain cancers.
- It can react with other natural substances in water to produce toxic by-products, which some people think could cause cancer.
What are the disadvantages of adding fluoride to drinking water?
- High doses can cause cancer and bone problems.
- There are concerns about whether it is right to mass medicate, meaning people can’t choose whether their tap water has added fluoride.
What is monitored in drinking water?
The levels of chemicals added.
