At first my horizontal nipples didn't have any water pooling. Now they do. The chickens use those nipples regularly, but still there is almost always a pool of water right below the nipple. And one of my nipples was leaking water, very slowly, but constantly - not from the insertion area, but from the nipple. I monkeyed with it and did get it to stop leaking, but that worried me a bit. It wasn't a simple bit of sand, as it took quite a while for me to get it to stop - and I"m not even sure what I did to make it stop.