SWIM is about to do another extraction for more of that amazing substance and he is planning to use Lazyman's tek. While reading the instructions SWIM noticed that it said mix the lye with 2 to 3 liters of tap water, wouldnt distilled water make a purer product or is there a specific reason it calls for tap water?

the reason it says to use tap water is probably because its free and easily available. For distilled water you'll have to pay for it, it will have had some energetic costs to make it, and it will make no difference at all in your final product. So no, distilled water wont really make a purer product (but it wont hurt if you do use it. I have used it once and there was no difference in final product in terms of yield or purity).

thank you, SWIM still has enough distilled water left from his last marsofolds extraction so its good to know he can use it.