Can we have manholes with a sewer system? Make it so you need a crowbar to open the manholes and make it really really dark with rare zombie encounters cause i dont think many would get down there and items are random. What will make it hard you might ask besides the dark, well the water is dirty so if you have wounds they will get infected bad and your shoes socks and pants will get wet and dirty unless you find water proof pants people wear in water to not get wet(add them). Maybe add storage rooms down there too. I just thought it would be fun to make people jumpy with the tight tunnels and extrem darkness, maybe have a lantern or flashlight.
