Just a general FYI to everyone about chemicals in tap water, sometimes when there's a break in a water main, municipalities dump extra chlorine into the system to compensate for reverse-seepage, and a lot of times it doesn't make the news. Brita water filters can only filter so much. If extra chlorine, fluorine, or sulfides are in your tap water, use bottled (spring) water for better results.
Changing what water you use is only part of it. I do recommend that, and checking the pH of your dough (not your water) if you have the capability. Other aspects of your ingredients may need to be reconsidered too. How fresh the flour is, the age of the yeast, the length of fermentation time, how airtight the retarding container is, how long does the dough sit in an aerobic environment before being placed in an anaerobic environment, are all things that determine acidity, alcohol levels, sugar levels, and amino acid levels which in the end affect browning.