ballcock
mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and (in the event of low water pressure) backflow
en-GB/ˈbɔːlkɒk/
en-US/ˈbɔlˈkɑk/
mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and (in the event of low water pressure) backflow