We installed the gas cylinder from our previous machine [that just broke after 10 years of use] thinking we'd use it up before installing the one that came with the unit. Our old cylinder was empty, of course it didn't carbonate the water. Next we overfilled the water bottle and of course it leaked. We filled the next bottle with the correct amount of water and no leaks. Funny how we were too stupid to read the instructions first. This new unit has several improvements over the previous models. Had I know about them I would have replaced my old unit much sooner. This new model is a hundred time easier to use. I am going to order a couple more for birthday gifts.