Originally Posted by drka0tic
The recommendation to use distilled water is not for temperature reasons but because of the damage that tap water can do to your components over a period of time.
Distilled water is treated to remove all the microscopic contaminants, along with dissolved minerals such as calcium and iron that are found in normal tap water.
Distilled water isn't "treated" it is just boiled and the steam is caught and turned back into water, that is a natural process that gets rid of everything from the water.
@op, you must have really clean tap water for your block to look that good after using tap water. The main reason people say to use distilled is because the quality of the tap water, is not always the same for every person. But distilled water is a guaranteed way to get clean perfect water. Some people do have clean enough tap water to use in their loops, other aren't so lucky.