Mississippi's capital city has too much water on the ground, and too little in the tap that's safe to drink. 

Parts of Jackson were without running water on Tuesday after heavy rainfall and flooding brought its ailing wastewater system near to collapse.

The city of 150,000 had already been under a boil-water notice for a month.

Restaurant owner Derek Emerson said water problems "are making it impossible for us to do business".

Mr Emerson and his wife, Jennifer, own the upscale Walker's Drive-In, and have been spending $US300 ($438) a day for ice and bottled water in the past month.

"I love doing business in Jackson, and I like the people of Jackson," Mr Emerson said. "I just — I hate dealing with the problems."