For the first time in more than a decade, Sydneysiders will face level one water restrictions, which are set to kick in on Saturday, June 1.

According to the Metropolitan Water Plan, water restrictions should come into effect when dam levels are at 50 per cent. They are currently at 53.5 per cent, but losing depth by 0.5 per cent each week, with no heavy rainfall in sight, triggering the restrictions prematurely. Sydney has experienced below-average rainfall for the past two years, and is officially in drought.

The restrictions will mainly apply to outdoor water use and affect Sydney, the Blue Mountains and the Illawarra. Households and businesses will only be allowed to water lawns and gardens with a hose fitted with a trigger nozzle before 10am and after 4pm. Paths, driveways and other hard surfaces will only be permitted to be hosed down for safety, health, emergency, construction or surface discolouration reasons.

Sydneysiders will be allowed to wash vehicles, trailers, boats and buildings, but only using buckets, high-pressure cleaning equipment or hoses fitted with trigger nozzles. As well as outdoor water restrictions, people are encouraged to limit how much water they use at work and at home.

Sydney's desalination plant was switched on in January when the dam level fell to 60 per cent. The plant provides up to 15 per cent of the city's drinking water. Sydney was last placed under water restrictions in 2003, with the limitations only eased in 2009.

For more information on how the water restrictions will impact you, visit Sydney Water.