Honestly the overclock will depend primarily on 3 things
1. the luck of the draw. some chips simply do not overclock as well as others
2. temp threshhold. typically you do not want this processor hitting over 85 degrees under load testing (so is a matter of what you are using to cool it
3. what you are comfortable with. personally i overclock my i5-3570k to 4.9 in the winter, then dial it back to 4.3 in the summer
With water cooling, assuming at least a 240mm radiator (fits 2 120mm fans on one side) you should be able to hit 4.6 easily enough, but anything after that will depend heavily on room temp, luck of the draw on your specific cpu, and a few other things like stability n such (always test with prime, but make sure you have your computer fully backed up n so on so that you are testing safely.