Bow drills are not that hard to make, but they do take a good bit of effort to get an ember, especially if you're somewhere humid.
What good is a water purifier without a pot to put the purified water in? ;)
Also, you can make a filter with soil and charcoal, if you can craft something to hold it so the water can pass through. Or just dig a well. If you can find a water source (creek or pond), you can dig a hole near them, and when you hit water it will be safe to drink.