How much water is used during the Reverse Osmosis process? November 05, 2024 17:54 Updated 1 Gallon : 5 Gallons For every gallon of RO water produced, the system will drain five gallons of water on average. Related articles What are the Benefits of Soft Water? How much fluoride does a reverse osmosis unit reduce? Replacing the Flow Control Insert How Does a Reverse Osmosis System Work? Diaphragm Replacement