using water in hydraulic brakes keeps coming up on here, generally its a bad idea, you need the correct oil in all brakes for lubrication etc alot of people use it in hs33's,but you MUST bleed regularly, and MUST add anti freeze, but its still abad idea!! (alot of stuborn people on here will say otherwise though?!?) NEVER EVER EVER use water in a disc brake though, amongst other things, disc brakes generate a huge amount of heat, water will just boil off andbecome useless! also it will rust and then seize the piston in the caliper body! Just dont be a cheapskate and use the proper stuff for the proper brake,its onlycheap anyway!! cheers Andy King