What is the required duration that reverse osmosis (RO) must run before water samples are taken for testing?

The correct duration for running reverse osmosis (RO) before taking water samples for testing is 15 minutes. This timeframe is vital because it allows the RO system to reach a steady state, ensuring that the water being tested has been adequately treated and is representative of the output generated by the system under normal operating conditions.

Taking a sample too soon may yield results that do not accurately reflect the system's performance due to the presence of initial contaminants or fluctuations in water quality as the system stabilizes. After 15 minutes, the system will have flushed out any stagnant water and impurities, providing a more reliable sample for quality assessment. This practice aligns with the guidelines for maintaining the integrity of testing procedures in water treatment systems, ensuring compliance with industry standards.