Place ground beef, water, onion, salt, and garlic powder in slow cooker.
Cook on high for about 2 hours, stirring occasionally (I stirred it twice throughout the day)
When meat is almost cooked through, stir again and turn your slow cooker down to low.
Cook an additional 1-2 hours.
Add in taco seasoning packet and give it a stir, then cook 20 more minutes.
Drain completely (will be a little liquidy from the water and some of the fat in the beef).
Serve over tacos, and freeze any leftovers so that you don't have to start from scratch the next time around!