What's the problem here?

MY CAR HAS A RATTLING NIOSE COMING FROM AROUND THE WATER-PUMP AREA..I DONT HAVE TO TOP UP SO DOES THIS RULE OUT THE WATERPUMP? IM NO EXPERT SO THATS WHY IM TRYING TO GET SOME ADVISE,IM WILLING TO TRY TO FIND OUT IF I CAN SAVE MONEY BY ME HAVING AGO,ONLY IM WORRIED ABOUT TAking the cam belt off in case i lnock it all out os symc!
any answers or advise is greatly appreciated/regards...
also is it ok to drive for the time being?
i have a 2003 citroen picasso 2.0l hdi..