The general rule of thumb is if your tap water tastes OK to you (as in not loaded with iron, sulphates, or other compounds that produce funky tastes or smells) then it will be fine for making mead. Most municipal water supplies in North America don't use enough chlorine to impede yeast development at all (especially after you've vigorously stirred the stuff to get your honey dissolved in it, and to aerate the must prior to pitching your yeast), but if yours seems particularly much like a swimming pool, you can either allow it to rest in an open container for a day or two, or you can boil it for a few minutes - but if you choose to boil, do so before adding your honey to avoid boiling off pleasant honey volatile aromatics and also allow it to cool to a temperature that won't stress your yeast before actually pitching.