I get 4-1 ratio, 4 gallons waste for 1 gallon pure. Honestly, you can drink the waste. Waste is such a harsh word for a RO/DI unit. The waste can be used for plants in the house or honestly for drinking. My TDS on my faucet is 114 and it's in the 80s on the waste water line. It's purer water than what I would drink, so why let it go down the drain in my opinion.