The depth of water seal in RCA latrine is

RCA latrine TRAP Latrine pan The trap is a bent pipe, about 7.5 cm in diameter and is connected with the pan. It holds water and provides the necessary 'water seal'. The water seal is the distance between the level of water in the trap and the lowest point in the concave upper surface of the trap. The depth of the water seal (AB) in the RCA latrine is 2 cm ( 3/4 in.). The water seal prevents the access by flies and suppresses the nuisance from smell. Ref : Park 25th edition Pgno : 796