Poultry Watering Nipples (4 pack). These screw-in watering nipples allow you to create a custom sanitary watering system with PVC pipe or plastic containers and feature a 360 degree stainless steel nipple-tip. Nipples are screwed into pipe or plastic container by drilling a 3/8" hole in the bottom of the pipe or container and inserted using pip-thread tape to make the connection water-tight.