hope this helps mate, i use 2 12mm plastic Tpieces.. you will pobs be better off using a copper one or something tho just make sure it can handle the hot water.
the 12mm was a bit too big for my turbo pipes but a bit of good old vasaline guided it on nicely. the original water feed pipes for my engine where a bit bigger so i just pushed them right on and used small jubilee clips to hold them on nice and tight.
as u can see my pipes are dirty this is because i first used cheap Tpieces and the plastic couldnt hadle the heat and broke. but i have had no problems since