i dont think we can preserve water raju?
thing is its constantly being used and recycled for example,we drink,we pee,it goes underground to the sewers where its collected ,cleaned and pumped back into our homes,well that's the system here in england,,,,elsewhere in the world,farmers water the land,the water seeps into the ground collects there ,we pump it out again,,same with rain water,everything stays on this planet,nothing goes anywhere,if it does its straight back into the soil.....what we can do raju is make better cleaning systems to purify contaminated water,because alot of countries are having problems accessing pure water..water is readily available everywhere,but its those remote areas where people need transport or some company bring the supply to them.
i understand what you are trying to say and its a fair comment,but to preserve water ,that kinda strange,coz no one does it as its used on a daily basis.