That's a very good point. If the hydro system is a closed loop system, I think that would eliminate any possibilities of wastes getting into the planet. Also, I'm sure there is a way to use 100% of the hydroponic water, possibly refine the waste water somehow? The hydro systems could even use organic nutrients so that water waste would be non-existent, leaving no damage or "salt" buildups in the land the waste goes to. These are just some thoughts I have. Aquaponics would be better yet. A system that relies on fish to feed the plants. The farmer only feeds the fish, the fish feed the plants and also keep the system clean. A mini ecosystem. With this system, there could be so many possibilities. It would have to be organic, so even the organic fans would be happy. It would grow fish AND plants for food. And there would be nothing in the system that would be bad for the environment in any way.