RO systems & flow restrictors

[Doug]

I purchased a Vectapure RO system and took it up north when I went for Christmas. Its a complete under sink install.

So the waste line also taps into the sink drain line. I have never used one this way, as ours have always drained into the washer stack. Anyways the waste line had a flow restrictor in it. Just a little insert in the line itself. All my drain lines have been wide open. Anyone else seen these?

Whats a normal waste ratio? Would it be 3-1, meaning wasting 3g of water to produce 1. Seems much to high for me but never checked into it myself?