How to tell if the urine bottle is full?

How do you know when a composting toilet's urine bottle is full?

One way would be to make a transparent bottle so that you could see when it was full.

But... pee scum is a real thing. More often than not, a transparent pee bottle ends up with lines all over the place - not very helpful.

So what did we do? We made a smart LED indicator light to tell you when it's time to empty Cuddy composting toilet's urine bottle. Done, Dusted, Problem solved.