Potable water quiz

1. What is meant by potable water?

a) Water that is safe to drink and has been treated to remove harmful substances.
b) Water that contains only H₂O molecules and no dissolved substances at all.
c) Water taken directly from the sea and used without treatment.
d) Any water found in rivers and lakes.

2. Which statement about tap water in the UK is true?

a) It is pure water containing only H₂O molecules.
b) It does not need to be checked for pH.
c) It is treated and disinfected to remove harmful microorganisms.
d) It comes only from underground aquifers.

3. Which of the following is NOT usually a source of raw water for making potable water in the UK?

a) Rivers, lakes and reservoirs.
b) Groundwater from aquifers.
c) Seawater used directly with no treatment.
d) Springs.

4. The process of removing salt from seawater to produce fresh water is called . One method that uses high pressure and a semi-permeable membrane is called .

5. Which pair of ions commonly cause hard water?

a) Sodium and potassium ions.
b) Calcium and magnesium ions.
c) Nitrate and phosphate ions.
d) Hydrogen and hydroxide ions.

6. Nitrates and phosphates washed off farmland can cause eutrophication. What is a key effect of eutrophication?

a) Increase in oxygen levels so more fish survive.
b) Algal blooms that reduce oxygen and can kill aquatic life.
c) Formation of more limescale in kettles.
d) Decrease in the number of bacteria.

7. Which method is most commonly used at the waterworks to disinfect drinking water in the UK?

a) Adding chlorine to the water.
b) Adding table salt to the water.
c) Freezing the water and then melting it.
d) Passing an electric current through the water.

8. What is an aquifer?

a) A machine used to pump water.
b) A lake formed by building a dam across a river.
c) A layer of porous rock or sediment that stores groundwater.
d) A tank at the waterworks used for sedimentation.

9. Which statement about desalination is correct?

a) It is an energy-intensive and expensive way to produce potable water.
b) It is the cheapest way to produce potable water everywhere in the world.
c) It can be done simply by adding chlorine.
d) It only works on river water, not seawater.

10. Which pH range is typical for safe drinking water supplied to homes?

a) pH 0–2
b) pH 3–5
c) pH 6.5–8.5
d) pH 12–14

11. Why is potable water not described as pure water?

a) It contains no dissolved substances at all.
b) It contains dissolved minerals such as calcium and magnesium ions.
c) It always contains dangerous bacteria.
d) It is only made by distillation in a laboratory.