I say, if water becomes much more valuable in the future, i say then give me more ways to get it!
example 1: rain-catchers. it'd be like a workshop that catches rain in barrels. when it rains, it fills up the barrel a little bit every couple seconds, and when it's full, a dwarf will replace it with an empty one. simple.
example 2: drink blood from animals. i've seen some african tribes on tv surviving off of water and the blood from cows and such. You just need a process of collecting blood from animals.
example 3: legitimate desalination plants. for oceans, pumping water through a corkscrew is sorta... weird. So lets create a water distillary. requires maybe a pipe section and some glass vials to build. how it'd work is like this, you put in a barrel of saltwater, and some charcoal or other fuel, and the the water is evaporated and recondensed into another barrel as fresh water.
example 4: service from the mountainhomes. instead of as a trade good, the king shows his appreciation for you by sending large parcels of water your way every season, and perhaps even constructing artificial rivers/aquaducts to your site if he likes you enough. of course this one is a farfetched one, and would probably require a couple more arcs to be done, but i'm leaving it out their.