Isle of Palms and Sullivan's Island residents are being asked to refrain from outdoor watering while a water main is being repaired.

A leak in the 20-inch main across Charleston Harbor from James Island to Sullivan's island was discovered Wednesday night and is being repaired, Charleston Water System spokeswoman Jenny Craft said Thursday.

The Isle of Palms is using its reverse osmosis plant and standby well to serve its customers and Sullivan's Island until repairs are complete, Craft said. The water might not taste the same but is safe to drink, she said.

Both islands have issued restrictions on outdoor watering while repairs are being made, and residents are asked to conserve water.

It was not known how long the pipe repair would take as of Thursday afternoon. The Water System will post updates at charlestonwater.com.

Reach Dave Munday at 937-5553.