This isn't a bug, but it is a rebalancing suggestion for watermills. I purchased a watermill to see if they are any good today. I think the watermill needs to be revalued somehow. Here's my reasoning. Everything you do in this game is to make troops to kill bandits or do adventures. To get troops you need copper/coal/iron. You've only got 6 copper mines which should easily supply your recruit needs, and 16 iron mines which more than supplies the need for iron, but coal you only have 6 mines. So for coal you try and run all of your mines, if you can't do that you are forced into a supply chain (fir forester, fir cutter, coking plants) which eats up building licenses. Coal is a pretty constrained resource because you only have so many building licenses and a set number of coal mines. So buying a recycling plant for coal at 900 gems isn't a bad buy. Now we should consider the 900 gem watermill. There is no limit to the number of wells on the map, the constraint is your population limit to operate them all, which with 1 noble house at level 3 you can support 50 wells if needed. Water really shouldn't be a constraining resource in any city as far as I can tell. So is a water mill that makes water at the same rate as a well, and is an odd shaped building really worth 900 gems? I don't think it even comes close to providing the same value as a recycling plant. If the watermill worked faster than a well, or cost a lot less gems I could buy into purchasing them out of the shop but right now the real winners in my city are clearly the +10 licenses, recycling plant, the geo/explorer/general.