The nipple water fountains stay clean. They are sealed.I've thought about trying the nipple waterer in the house, but I always used a regular waterer in the run set up on a concrete block to keep it off the ground for my last flock. Right now the block is too high for these girls to use yet so I'm just using regular small square blocks to keep it off the ground. We get a couple months of freezing temperatures so I don't think the nipple waterer would work out well in the run. They are quite messy at this age, so I have had to clean them daily and sometimes 2 or 3 times a day.