I remember when they banned rainwater tanks !

Alison Jane,
Recycling water can be cheaper if it's meant for irrigation however, for human consumption it's still way too complicated & costly to make it worthwhile. Desalination is viable for small communities but for large cities the reject outflow poses massive problems down the line after a while.
Flood mitigation is the only other viable alternative wherein canal developments can be mated to settling ponds & the real estate alone can just about pay for it all.
All it needs is to offer the Greenies to demonstrate how they can make ends meet through merit rather than just being hanger-on bureaudroids. That too would free up capital for sensible irrigation & infrastructure projects.
Keep the academic experts away from anything infrastructure & all will come good !