Reverse Osmosis Output and Drain Ratio by Membrane and Pressure

What a rated membrane actually produces at household feed pressure and temperature, rather than at the 60 psi and 77 degree laboratory test conditions, plus the gallons to drain per gallon made.

Every page below is computed rather than written, from the same formulas the matching calculator uses, so a figure on a chart page and the same figure in the calculator cannot disagree. Each one carries its working, the basis of every number it prints, and equipment chosen by those numbers rather than from a general list.

• What does a 50 GPD reverse osmosis membrane actually make at 35 psi? A 50 GPD membrane at 35 psi and 60 degree feed water makes about 14.3 gallons a day, not 50. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 50 GPD reverse osmosis membrane actually make at 40 psi? A 50 GPD membrane at 40 psi and 60 degree feed water makes about 16.3 gallons a day, not 50. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 50 GPD reverse osmosis membrane actually make at 50 psi? A 50 GPD membrane at 50 psi and 60 degree feed water makes about 20.4 gallons a day, not 50. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 50 GPD reverse osmosis membrane actually make at 60 psi? A 50 GPD membrane at 60 psi and 60 degree feed water makes about 24.5 gallons a day, not 50. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 50 GPD reverse osmosis membrane actually make at 70 psi? A 50 GPD membrane at 70 psi and 60 degree feed water makes about 28.6 gallons a day, not 50. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 75 GPD reverse osmosis membrane actually make at 35 psi? A 75 GPD membrane at 35 psi and 60 degree feed water makes about 21.4 gallons a day, not 75. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 75 GPD reverse osmosis membrane actually make at 40 psi? A 75 GPD membrane at 40 psi and 60 degree feed water makes about 24.5 gallons a day, not 75. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 75 GPD reverse osmosis membrane actually make at 50 psi? A 75 GPD membrane at 50 psi and 60 degree feed water makes about 30.6 gallons a day, not 75. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 75 GPD reverse osmosis membrane actually make at 60 psi? A 75 GPD membrane at 60 psi and 60 degree feed water makes about 36.8 gallons a day, not 75. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 75 GPD reverse osmosis membrane actually make at 70 psi? A 75 GPD membrane at 70 psi and 60 degree feed water makes about 42.9 gallons a day, not 75. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 100 GPD reverse osmosis membrane actually make at 35 psi? A 100 GPD membrane at 35 psi and 60 degree feed water makes about 28.6 gallons a day, not 100. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 100 GPD reverse osmosis membrane actually make at 40 psi? A 100 GPD membrane at 40 psi and 60 degree feed water makes about 32.7 gallons a day, not 100. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 100 GPD reverse osmosis membrane actually make at 50 psi? A 100 GPD membrane at 50 psi and 60 degree feed water makes about 40.8 gallons a day, not 100. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 100 GPD reverse osmosis membrane actually make at 60 psi? A 100 GPD membrane at 60 psi and 60 degree feed water makes about 49.0 gallons a day, not 100. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 100 GPD reverse osmosis membrane actually make at 70 psi? A 100 GPD membrane at 70 psi and 60 degree feed water makes about 57.2 gallons a day, not 100. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 150 GPD reverse osmosis membrane actually make at 35 psi? A 150 GPD membrane at 35 psi and 60 degree feed water makes about 42.9 gallons a day, not 150. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 150 GPD reverse osmosis membrane actually make at 40 psi? A 150 GPD membrane at 40 psi and 60 degree feed water makes about 49.0 gallons a day, not 150. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 150 GPD reverse osmosis membrane actually make at 50 psi? A 150 GPD membrane at 50 psi and 60 degree feed water makes about 61.3 gallons a day, not 150. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 150 GPD reverse osmosis membrane actually make at 60 psi? A 150 GPD membrane at 60 psi and 60 degree feed water makes about 73.5 gallons a day, not 150. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 150 GPD reverse osmosis membrane actually make at 70 psi? A 150 GPD membrane at 70 psi and 60 degree feed water makes about 85.8 gallons a day, not 150. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 200 GPD reverse osmosis membrane actually make at 35 psi? A 200 GPD membrane at 35 psi and 60 degree feed water makes about 57.2 gallons a day, not 200. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 200 GPD reverse osmosis membrane actually make at 40 psi? A 200 GPD membrane at 40 psi and 60 degree feed water makes about 65.3 gallons a day, not 200. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 200 GPD reverse osmosis membrane actually make at 50 psi? A 200 GPD membrane at 50 psi and 60 degree feed water makes about 81.7 gallons a day, not 200. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 200 GPD reverse osmosis membrane actually make at 60 psi? A 200 GPD membrane at 60 psi and 60 degree feed water makes about 98.0 gallons a day, not 200. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 200 GPD reverse osmosis membrane actually make at 70 psi? A 200 GPD membrane at 70 psi and 60 degree feed water makes about 114.3 gallons a day, not 200. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 400 GPD reverse osmosis membrane actually make at 35 psi? A 400 GPD membrane at 35 psi and 60 degree feed water makes about 114.3 gallons a day, not 400. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 400 GPD reverse osmosis membrane actually make at 40 psi? A 400 GPD membrane at 40 psi and 60 degree feed water makes about 130.7 gallons a day, not 400. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 400 GPD reverse osmosis membrane actually make at 50 psi? A 400 GPD membrane at 50 psi and 60 degree feed water makes about 163.3 gallons a day, not 400. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 400 GPD reverse osmosis membrane actually make at 60 psi? A 400 GPD membrane at 60 psi and 60 degree feed water makes about 196.0 gallons a day, not 400. The test conditions behind the rating, the temperature correction and the drain ratio.
• What does a 400 GPD reverse osmosis membrane actually make at 70 psi? A 400 GPD membrane at 70 psi and 60 degree feed water makes about 228.7 gallons a day, not 400. The test conditions behind the rating, the temperature correction and the drain ratio.

Researched, not professional advice. Every figure on these pages is labeled as a published standard, a trade rule of thumb, or something that can only come off your own water test. Where a published figure does not exist we say so rather than estimating one. Test your water before you buy equipment: on city water start with the Consumer Confidence Report your utility publishes each year, and on a private well only a certified laboratory test tells you what you have. Bacteria, nitrate, lead, arsenic and PFAS are not do it yourself topics and need a laboratory and usually a licensed professional.