What's a simple way to add waste to under sink?

[pedr0]

Hmm. So have both fresh supply and recirc. Use the fresh supply when the reservoir is low, and the recirc when the reservoir is high.

Or even, irrigation is only ever from the reservoir. But have a secondary filling system that adds a bit to the reservoir when it gets too low. Definitely graceful.

The recirc pump will temporarily lower the reservoir level when it's actually in operation pumping the water to the top of the wall (this will only happen a couple of times a day). So I'll have to think about how to ensure the refilling doesn't get confused and fill at those times because that will lead to the reservoir overflowing as the water slowly trickles down the wall.

If my refilling supply is teed off from my mains 15mm copper pipe under the sink, is there a valve that can be controlled by a float switch? I guess some sort of electronic valve? (As I write this, it's starting to feel complicated )

 

[Lower]

Have a reservoir at the top with a float switch in, and a pump at the bottom with a float switch. Make the reservoir at the top twice the size of the reservoir at the bottom, and set the float switch halfway up the top reservoir. Connect the incoming water supply to the float switch. When there is no water in the reservoir, the reservoir fills up from the incoming supply. When the pump starts pumping water from the bottom to the top, it will fill up the reservoir at the top and cut off the incoming supply. As the reservoir at the top can contain the normal fresh supply and the volume of the reservoir at the bottom, no risk of it overflowing.