Radiator Loosing Water

[SBM]

have an ongoing problem with my 2005 ford focus 1.4. I have to add at least 1 litre of water into my water reservoir (plastic thing that fills the radiator) each day. The water disappears once I have been driving, more disappears over a longer journey. The water stays in if the engine has not be running. A mechanic has pressure tested the plastic reservoir but states it is holding all pressure they put into it (no leakage), also the cap has been replaced to ensure that it is sealing and not letting off steam. The engine appears to be running fine and the oil looks as it should.

Can anyone please advise, as I think the mechanic has given up??

Thanks,

[artscot79]

If its losing water then its either water pumps leaking the radiators leaking theres no way hes pressure tested it if its losing water unless the engines running so hot its boiling the coolant away quite simply it wont dissapear so theres a definate problem ide suggest a different garage