Welcome to the Shroomery Message Board! You are experiencing a small sample of what the site has to offer. Please login or register to post messages and view our exclusive members-only content. You'll gain access to additional forums, file attachments, board customizations, encrypted private messages, and much more!
Water is used in the different stages of growing. I think you are referring to the water used to make substrate. If so, simple tap water should be enough for this, remember that it's going to be sterilized when PCing the jars. There are some extreme cases though, where tap water is heavily polluted, using bottled water is a good solution if any problem arise. Using H2O2 before PCing is useless, it degrades and breaks up at high temperatures.