I don't think Bertha does. The grey waste tank is a big bugger underneath the rear wheels. I've never really paid it much mind TBH except for emptying it when I suppose it's nearly full. The gage has never worked so I just guess. Paying for that blasé attitude now though. I know there's plenty of gunk in there, but when I released the pipe and opened the valve, nothing happened. Uh oh.Also waste tanks often have an inspection hatch so you can access the inside