Design a machine that will go down the pipes and remove the oil and blockages from the system. It should be able to scoop away solidified fat and ensure that the walls are clean.
Create a leaflet which tells people about water wastage and think of ways we can save water.
Make a scale model of the ring main around London and then one of the outlets going to households.
Discuss the need for underground telephone lines. Do we need them now we have mobile phones? If war were to break out what would happen?