Technically speaking: One ...

Technically speaking:

One way of achieving best practices is to take in account the amount of energy we use in the water supply system. Many times we have systems were we can use much less energy than we are really using. Sometimes this goes from the conception of the system itself. Sometimes in hilly cities we have a succession of pumping stations and energy lost valves when we can think in better ways of not doing that. Other times the pumping stations aren't enough effcient because they are dimensioned to work in several stages of pumping, very different between them. In this case I will recommend an elevated tank before the network and one pumping station to the tank, design to work to just one stage of pumping.

Policy making:

Using preferably the storm water (dams and reservoirs) instead of using groundwater. This saves the water on the ground and helps to prevent desertification and it prevents the salt from the see to arrive to the groundwater in costal areas (wish leads to desertification too). 

Doing a balance between the needs of water and the amount of water that actually exists or may be collected is a very good exercice to do. If we are heading to a shortage of water, it' better to be prepared before and not growing big cities or industrial zones.