Float valves (also known as ballcocks, inlet valves, fill valves or ball valves) are valves that control the flow of water into a cistern or tank so that it is filled to a set level. They are used in WC toilet cisterns, loft / attic cold water tanks and central heating feed / expansion header tanks.

BS1212 is the British Standard number for float operated valves. There are 4 parts to the standard :

BS1212/1 Part 1 brass ballcock / float valves are used in cold water tanks, central heating feed / expansion header tanks and old toilet cisterns.

BS1212/2 Part 2 brass ballcock / float valves are used in cold water tanks, central heating feed / expansion header tanks and (very rarely) toilet cisterns.

BS1212/3 Part 3 plastic ballcock / float valves are used as inlet / fill valves in older (handle flush) WC toilet cisterns.

BS1212/4 Part 4 plastic ballcock / float valves are used as inlet / fill valves in modern WC toilet cisterns.

The threaded connections of these ballcock valves use a British Standard Pipe Thread size - see BSPT link at bottom of page for more info.