Why it is for you

This is the mixing liquid for the person who mixes a vial and uses it straight away, or whose powder comes with a maker instruction naming preservative-free water. It suits a single large dose drawn in one sitting. If instead you plan to mix one vial and draw from it daily for two to four weeks, bacteriostatic water is the better partner, because it is built to be entered again and again. Pair it with whichever powder you are starting, and keep a few on hand: they cost little and they end the guesswork.