These poultry drinking cups are made of high quality, UV resistant plastic.  The drinker works by way of a float valve: As the cup fills with water, the yellow arm starts to float and the supply is shut off.  These drinkers are easy to clean and provide a consistent supply of fresh water. These can be attached directly to a heavy base bucket, 20L container or pipe.  Ensure its is plastic so it can drilled (using a 8.5/9 mm drill bit) and threaded.  The drinker cup has a tapered thread, so will self-tighten as you thread it onto the container.