We do this in some cases, but in general oil is expensive and water is cheap. A gallon of crude oil costs around $2.50. A gallon of tap water costs a little ove

We do this in some cases, but in general oil is expensive and water is cheap. A gallon of crude oil costs around $2.50. A gallon of tap water costs a little over a penny where I live (in San Francisco). Transporting expensive things is an easier sell than transporting cheap things.