You can use tap water. Your humidifier will work, then hate you. It’ll cough out white dust, smell like a gym sock, and die young.
Or you can use distilled. Your humidifier becomes a zen master. Clean, quiet, immortal (almost). Your furniture stays normal. Your nose stays happy.
So, do you need distilled water? For joy? No. For sleep without a dusty nose? Yes. The choice is yours, humidifier warrior. Choose wisely.
P.S. — If you use tap, don’t forget to clean weekly with vinegar. Your humidifier will forgive you… eventually.