What kind of water works best? Does it even really matter what kind you use for an STB extraction, last time I used distilled and got a better yield than my first fews times, but that may be because of a better MHRB vendor..... What are all of your thoughts on the subject?

Well, distilled water in general is always the best to use for any organic chemistry experiments!
Not sure how much using regular water affects it though, doesn't seem like it should make much of a difference, since extraction tek's involve only one-two reaction steps!

You would probably only need to use distilled water if you were planning to make dmt-freebase for injection purposes, then you need to ensure your product is 99% pure.

A lot of times tap water can be slightly acidic or basic, but I am pretty sure that water treatment facilities make the water slightly basic so it doesn't corrode the lead pipes for the plumbing. I don't know about well water. I do know that water in nature is slightly acidic b/c dissolved CO2 reacting with water to make carbonic acid. Either way this shouldn't have too much effect. Just make sure that the ph of water is right depending on the tek u r using.

There are other impurities in tap water though, like various dissolved ions. If you are really worried about contaminants in your tap water you can distill your own water. There are a few ways you can do this ranging from the complicated setups you would see in a chem lab to really simple even primitive ways. The more simple home distillations won't give you pure water but it will be very close if the necessary precautions are taken.

I use reverse osmosis water, you can pick a gallon up at walmart or other big stores for 39 cent refills on a gallon or just over a dollar if you need the container too. But any type of water should work. I just don't like using or drinking for that matter fluoridated water, and whatever else is in municipal water.

Distilled water is cheap and is the standard for good chem practice, but for this extraction, any water will work just fine. pH shouldn't matter as you're going to acidify and basify it anyway...so no real issues there. Overall, the water you choose to use should have minimal influence on your final yield.

If your experiment involves evapping I would discourage using tap or even filtered water. I know my tap water is very "hard," ie, it has a lot of dissolved caclium and other minerals, which leave a pretty hefty residue on evapping, along the lines of 50mg salts for 200 ml tap water even after filtering. An evap and ph test on tap water is very interesting besides any chemistry you might want to do. Especially if you are drinking it all the time...