Water is used because it is requires about one third of the quantity of oil cooling having a better cooling qualities than oil thrugh it being able to operate at Higher temperatures.
A centrifugal pump supplies the cooling water under pressure to the Piston Crown where it is circulated through water channel that has been cast into the Piston Crown.
These channel are positioned close to the walls and top of the crown, also behind the piston ring grooves to promote optimum cooling of the surfaces of crown subjected to high high temperature.
The water enters and leave the Piston through telescope pipe that slide up and down on a standpipe as piston reciprocates. These pipe have rubber water seal between them to prevent leakage of cooling medium into the crankcase lube oil.
These can we also cooled enclosure around the seal that incorporated tell -tale leak pipe that eject water if seal begins to leak.
The pipes are located at convenient location outside the engine crankcase.