Meters fitted with leak alarms will save Southern Water customers five million litres of water per day, the water firm estimates.
Southern Water's universal meter programme is due to be completed by 2015. It is installing built-in leak alarms that are triggered when pipes inside or outside a home spring a leak.
The company says one in five leaks occur in the supply pipes linking households to water mains. Although homeowners are responsible for fixing such leaks, Southern Water is offering to repair up to three free of charge.