How often do you change your coolant mixture?

...And why?

I just realized I have been running my system for a while. Is there any reason why I should change the water? If I should, then should I use the same mixture I've had since I first filled it. I only used about 1/4th of the gallon that I mixed. Or should I buy a new gallon of distilled?

i've changed my water twice in two years. the first time because i was changing some components, and the second time because i was moving everything to a new tower and changing some components. . i would think that barring any other problems, changing your water once a year would be fine.


J.