waist-deep water. >> i saw one workman, david, who was ducking down under the water trying to pull these sandbags out. another man had hold of his hand. >> the worker successfully removes all but one of the bags, but there's one last bag still blocking the drain. david dives into the murky water to grab it. >> nobody sort of realized what had actually happened because everyone had thought, oh, he's just pulling another sandbag up. when he didn't come back up, all hell broke loose. >> the force of the water on top of the bag pushed it through the drain and took him with it. he was above the water, still at that stage, but his legs were wedged into the pipe. >> by removing the bag, david unplugs the drain, and now the pressure of the gushing water pushes so forcefully, it sucks david's legs into the drain. >> i jumped into the water to try and help remove him from the