There are two basic categories of water shut-off systems: whole-house systems and point-of-use systems. While both can prevent water damage, generally only a whole-house system qualifies for a premium credit on your homeowner insurance.
WHOLE-HOUSE AUTOMATIC SHUT-OFF SYSTEMS
Whole-house automatic water shut-off systems that detect or prevent water damage from internal plumbing leaks usually are either time/flow-based or sensor-based. Each uses a different technology to detect leaks, and each can be tailored to match the needs, lifestyle and usage patterns of any homeowner. Note that whichever system is used, installation should be completed by a licensed plumber.
Time/flow-based systems constantly monitor water flow through the pressurized plumbing lines of a home. Some use machine learning to establish typical usage patterns. In most systems, settings can be adjusted to accommodate user and appliance water use habits. Settings can be based on continuous length of time or on maximum continuous gallons needed for daily activities.