United Utilities were alerted to the issue in the PR1 and PR5 areas at around 12.40pm on Saturday (July 16).
The supplier said homes were left without water due to a burst main at Capitol Centre Retail Park in Walton-le-Dale.
“Our team will be on site as soon as possible,” a spokesman for United Utilities said.
“Sorry for any inconvenience, we hope to have things back to normal soon.”
In an update at 4.45pm the same day, United Utilities confirmed water was starting to be delivered from a different area so taps could start to flow again.
A spokesman for the water supplier said: “Please be assured, we will still be providing you with the same high standard quality of water.
“However, it may mean your water pressure may be lower than normal or you might notice fluctuation during peak times.
“We’re sorry for any inconvenience this is causing, and thanks again for your patience.”
The incident came as temperatures were predicted to reach 22C in Preston, with warm temperatures expected for the rest of the day.
United Utilities said when they need to fix a major water main, which might supply lots of customers, they will make other sources of water available within 12 hours.
This could involve tankers of water in the street or free bottles of water for those affected.
A spokesman added: “If we don’t, you can claim £20 in compensation.”