I watched this last night,they reckon were in our second dry winter(not sure if regions vary),but if we go through a third dry winter,drastic measures could be taken if water levels continue to decline,at one point a guy was saying that households could have there water supplies cut off and standpipes put up in streets,you would have to take water by bucket for what you needed for your daily use,this is of course if it got that bad.
Although there was someone on there from government saying they did have backup plans in place,but no one knows how effective this would be,as we have never gone through a third dry winter.
Spain have built a giant filtering plant,and suck water from the sea as a backup measure.
Personaly I think when they build any new housing they should put in rain water tanks as standard,and also the government should do some form of subsidised scheme to install them om existing properties.
Regards Brian.