I use the kind of system you are describing. Since I am on a septic system, I certainly can't drain hundreds of gallons of water into my drains, so my single pump ejects the water to the outside. I have bulkheads in all my tanks; faucets screwed into the bulkheads; hoses attached to the faucets, all running into a manifold attached to the inlet of the pump. In warm weather, the outlet of the pump is run to a buried line that drains into a field next to my yard. Flipping a valve diverts that water to a faucet mounted outside; I can then use the water for plant watering, etc. In the depths of winter, I must attach a hose to that faucet and run the waste water out into that same field. Laying the hose out and then coiling it up afterwards is the main downfall of my system...but if you don't have the limitations of being on a private septic system, then this method is simple, largely maintenance-free, pretty foolproof and...once set up...saves you a ton of time and effort when changing water.
