Push the Tubing All the Way in and Use Teflon Tape During Installation. The 6th stage is DEIONIZATION FILTER. TDS value of pure water close 0 ppm. Mixed bed DI filter is used to further remove TDS from membrane filtered water. Premium ceramic disc operated, Lead-free ro drinking water dispensing faucets.Faucet has a mounting range of ½"- 1 ½" for installation in a sink or countertop. Wastewater ratio is 1:2. NSF certificated Thin-film composite RO membrane filters with higher water production rate. 2 gallons wastewater will be produced for every gallon pure water.