I had the water pump replaced in Jan 2012 and am still loosing water everyday

How do I do a pressure test or do I take it back to the garage to see if he messed up

The pressure test takes special equipment. If you suspect that the repair was done improperly or that the part they installed has failed prematurely, then you should take it back to them. Mistakes, unfortunately, do occur. Give them the opportunity to make it right. You may be surprised, then again, cooling systems can be very complicated and involve a great many parts located in very close proximity. Good luck!

GOOD QUESTION SINCE IT IS ALMOST NOVEMBER!