Every vial entry is the risk moment
The moment a needle pierces a septum is the highest contamination risk in any protocol. The preservative in bacteriostatic water (0.9% benzyl alcohol) exists precisely to survive that moment, but preservative is a safety net, not a substitute for technique.
Wipe the septum with a fresh sterile alcohol pad before every entry. Let it dry before piercing; wet alcohol is a transport medium, not a sterilant.
Surfaces and hands
A clean bench is a prepared surface, not a tidy one. Wipe the work area with 70% isopropyl before starting, and work on a fresh barrier. Nitrile gloves are not optional, and they are single session: the gloves that handled your phone are not bench gloves.
Storage discipline
A multi-dose vial of bacteriostatic water is good for weeks, not months. Refrigerate after first entry, date the vial, and discard on schedule rather than on appearance. Cloudiness, particulates or any colour change is an immediate discard regardless of the calendar.
Consumables are single use
Needles and syringes are single use by design. Reuse deforms the needle, blunts the bevel and multiplies contamination risk. The marginal cost of a fresh sterile unit is trivial next to the cost of a compromised protocol, which is exactly why our kits pack consumables the way they do.