How should connections for rainwater catchment be marked?

Connections for rainwater catchment should be marked with a caution message that clearly indicates the water is non-potable and not safe for drinking. This designation is crucial for public health and safety, as it helps to prevent accidental consumption of water that is not treated or purified to meet drinking water standards. Since rainwater is collected directly from rooftops or surfaces, it may contain contaminants that can pose health risks if ingested.

Marking the connections as "CAUTION: non-potable water; DO NOT DRINK" serves to inform users about the potential hazards and reinforces the importance of using the water only for appropriate non-drinking purposes, such as irrigation or landscaping. This clear labeling helps ensure compliance with safety regulations regarding water catchment systems and protects individuals from unintended exposure to untreated water.

The other options do not provide the appropriate clarity or safety warnings needed for rainwater catchment systems, leading to potential misuse or misunderstandings about the nature of the water.