Which of the following must be true for a project that meters alternative water sources to comply with Indoor Water Use Reduction - Option 2?

A project that meters alternative water sources to comply with Indoor Water Use Reduction - Option 2 must allow for flexibility in how the water use is measured. When a project meters alternative water sources, it is valid to meter these sources either separately or alongside the potable water use from fixtures. This means that the project can choose to keep track of the alternative water use in isolation to evaluate its specific savings or integrate both types of water use for a comprehensive assessment.

This approach supports a broader understanding of water usage on the property, accounting for the contributions of alternative sources, which is essential for projects aiming to reduce overall indoor water consumption. It encourages the effective use of resources and provides insight into the efficiency of the systems in place. By allowing for this flexibility, projects can demonstrate compliance with the specified indoor water use reduction requirements more effectively, optimizing their overall operational performance.

The other choices do not align with the guidelines for metering as they limit the potential for assessing water use in a holistic way or misinterpret the metering requirements.