Around 10,000 homes across the Horsham district were left without water last night after a sudden drop in water pressure.
Crews from Southern Water worked throughout the evening to restore supplies to those affected in Maplehurst, Henfield, Partridge Green, Cowfold, West Grinstead, Dial Post, Coolham, Mill Straight and Southwater.
Southern Water say they are now investigating what caused the drop in pressure.
A spokesman said: “Our crews worked throughout the evening to restore supplies to our customers and we began to rezone water at around 8.30pm.
“The water supply and pressure was restored to those affected areas over the next couple of hours. We believe all affected customers are now back in supply.
“We advised customers they may notice some discolouration when they first started to run the water; but assured people this is completely normal when there’s been a disruption in supply and is only temporary.”