I would have been interested to understand the comparative cost to build and run a desalination plant compared to the costs for the new resevoir.  Also how the security of the supply for these two options were considered since resevoires appear less secure.

Water meters in blocks of flats should also be considered since many new developments for ageing residents have been built and are no doubt planned where many services are provided and costs shared between the flats thereby individual accountability is undermined.

Considering how to encourage the use of water butts by rebates on bills perhaps.  We have a water meter so when I use our own stored water from the water butt it reduces my costs anyway but it might also be a way of encouraging their use.

Has any work been done on estate planning for the reuse of rainwater run off to underground storage tanks and how that could be used either by residents for their gardens and car washing etc, or indeed by Portsmouth Water as another potential source of water?