Have you taken advice from a Dietician about this ? You would normally be advised by a Dietician if you need to follow a special diet. The advice you are given will depend on how well your kidneys are working, your blood test results and your own preferences about what you normally eat and drink.
The National Kidney Federation says that there is no special diet needed.......however if you already have Kidney damage then it may be that you need to limit intake of certain things, proteins etc.
Only a dietary expert can advise you what is the correct protocol........what is right for one person MAY NOT be right for you taking into account your particular circumstances and medical history. Hence I wouldn't advise you what is a safe limit for YOU.
We do have one recognised Dietician here who may be able to advise you in general terms......if she sees the post......