What action is necessary during the initial startup of a reverse osmosis system?

During the initial startup of a reverse osmosis (RO) system, it is essential to pressurize the system. This action allows the components of the system to function properly, ensuring that the water is adequately forced through the RO membrane. Pressurizing the system also helps to identify any leaks or issues that may arise during operation, thus allowing for adjustments or repairs before the system is fully operational.

Additionally, pressurizing prepares the system for filtration, as the RO process relies on a specific pressure differential across the membrane to separate contaminants from the water effectively. Without proper system pressure, the RO system may not perform as intended, leading to water quality issues or system failure.

Other options, such as measuring reject flow, installing the faucet, or connecting the water supply, are also important steps in the setup process but do not play a critical role in the initial startup phase. These steps typically follow after ensuring that the system is pressurized and ready for operation.