What is a Reverse Osmosis Calculator?

A Reverse Osmosis (RO) Calculator is an essential technical tool used by water treatment professionals and homeowners to evaluate the efficiency and health of an RO membrane system. It analyzes four key data points: Feed TDS (Total Dissolved Solids), Permeate TDS, Feed Flow Rate, and Permeate Flow Rate. By calculating these metrics, you can determine if your membrane is fouling, scaling, or reaching the end of its functional life.

Understanding RO Performance Metrics

There are three primary indicators of a healthy reverse osmosis system:

• Salt Rejection: This indicates the percentage of contaminants the membrane is successfully removing. A typical high-quality RO membrane should have a salt rejection rate between 95% and 99%.
• Recovery Rate: This measures how much of the water entering the system is being recovered as purified product (permeate). While higher recovery saves water, it increases the concentration of salts on the membrane, potentially leading to faster scaling.
• Salt Passage: Simply the inverse of rejection, this tells you exactly what percentage of salts are "slipping through" the membrane barrier.

How to Use This Calculator

To get accurate results, follow these steps:

1. Measure the TDS of your raw incoming water (Feed) using a TDS meter.
2. Measure the TDS of the purified water (Permeate) coming out of the RO faucet.
3. Record the flow rates of both the input and the product water (usually in Gallons Per Minute or Liters Per Minute).
4. Input these values into the calculator above and click "Calculate Performance".

Frequently Asked Questions

When should I replace my RO membrane?
If your salt rejection rate drops below 90% or your recovery rate significantly decreases despite constant pressure, it is usually time to clean or replace the membrane.

Does temperature affect these readings?
Yes, water temperature significantly impacts RO performance. Cold water increases viscosity, which reduces permeate flow, while warmer water increases flow but may slightly decrease salt rejection.