This kind of thing is basically why I'm not interested in water cooling. Even AIOs would technically need maintenance and replacement after a while. And the worst part of an AIO, is that you're not even able to see inside the loop if something goes wrong.
The only way to do water cooling right, is to do a custom loop, which would necessitate constant maintenance and praying that the pump doesn't fail, or that water doesn't leak and burn something.
Meanwhile, I've yet to witness a stock cooler air fan fail. I'm not even talking about some supreme after market master race cooler here. I'm talking about cheap stock stuff being more reliable and risk free.