Water, water everywhere....
Everyone is familiar with this quotation from The Rime of the Ancient Mariner by Samuel Taylor Coleridge - or think they are. It was actually written thus:

Water, water everywhere

and all the boards did shrink

Water, water everywhere

nor any drop to drink.

In Britain we have an imbalance of rainfall: the north is adequately supplied but in the south a drought has been declared in several counties.
When the Grand Junction Canal was built over Tring summit about 200 years ago the banks were porous and water seeped from the water table into the canal constantly maintaining the level.  Increases in water extraction and changes in climate have resulted in the water table now falling below the level of the canal.  Consequently the water seeps in the opposite direction   This has been measured as 16 million litres per week. Currently the  total consumption of water in UK including all that used in the production of imported food and textiles is calculated as 4645 litres per person per day.  Diet has an impact: a meat and dairy consumer will use 5000 litres: a vegetarian, 2000 litres. Direct consumption of water is about 38 litres per person per day on average. Our direct consumption on the boat is about 38 litres per person per week.
So the canal leakage would satisfy the direct water requirements of over 60,000 people ( or 421,000 boaters )
It seems to me that rather than spend £X squillions on a high speed railway to take people from London to a new station in Birmingham which is not connected to any other railway we could improve our water resources by lining the canal from Marsworth to Cowroast and still have change to improve the current rail network.