My mothers mother was Lipan Apache and the acorn was a main stay for them and the following is from what she told me and from personal experience. Any of the ways stated by wildman800 and blast will work. However it is best not to crush the acorns before hand because it affects the taste IMHO in a bad way. If as wildman800 suggests and you use the water to tan your hides keep the water but if your not going to use it in that manner it is best to change the water better.