Paul Crease, licensee of the Arun View in Littlhampton, said he stayed on the premises after locking up, having been warned about the expected high tide.
He said: “We hung about until high tide at one o’clock, when water came up through the storm drains and into our cellars.
“Thankfully the front side of the pub on the river side was protected by a flood defence scheme several years ago unlike the other side of the river.
“I’ve never seen water break the banks like that in all the years I’ve lived here.
“It was awful seeing that amount of water going through the properties, and literally nothing anyone can do.”