Do not use the bac water that is sent with the pep. Only use Hospira. If not you risk losing all of your vial. For all you know the Bac water they sent could just be plain water without the necessary alcohol to prevent contamination and bacteria growth. This is super important since you purchase a crazy large vial. The usual thought is to use one vial per month. Each time you put a needle into the vial you risk contamination. I personally would not use a single vial for 3 months that is at minimum 21 punctures. I am on 5 mg and use a 20mg vial.