Wouldn't be worth it. The largest super tankers have a deadweight tonnage of approximately half a million tons, which is worth ~$500MM of crude oil. But water

Wouldn't be worth it. The largest super tankers have a deadweight tonnage of approximately half a million tons, which is worth ~$500MM of crude oil. But water is super cheap by comparison. Assuming $0.0015/L (which is what I pay for my tap water in California), half a million tons of water is worth only $750k. Another way to see it: the transport cost per super tanker is about $0.02 per gallon [1] but tap water is ~$0.006 per gallon (again, my tap water cost). So you would be tripling its cost to transport it by sea... [1] http://en.wikipedia.org/wiki/Oil_tanker http://en.wikipedia.org/wiki/Oil_tanker