That has to be one of the worst installations I have ever seen of a gas water heater. (And I have seen it all in 50 years) You don't use a washer hose to hook up the water lines on a heater especially on the hot side. The flue pipe needs to be connected and screwed together. You have a very serious fire hazard there. Not to mention the carbon monoxide hazard. I can't see the gas line but I can just imagine what that looks like. First thing to do is turn it off before someone gets hurt. Then call a real plumbing contractor to re-do the install. Before doing so save the pictures you have taken and show them to the building dept. so they can take action against the installer.