.22 sterile filter
1ml sterile BA
100ml sterile vial
20ml syringe
two 18g pins one for drawing water and one for injecting in sterile vial.
small pin 27g for letting air pressure out of vial you injecting BA into
There's no need to boil your water or anything like that. Simply buy a sealed gallon of distilled water. Set up your vial to be filtered in to by placing one of the 18g needles in the top with the filter attached, as well as the 27g needle in the top for air exchange. The pins used for injecting into the sterile vial and relieveing air pressure should stay there with the filter until the process is complete. Use the 3rd pin to draw the water with. You will be switching the syringe from the filter to the drawing 5 times or so to get 100ml.
Now put 1ml of BA through the filter, in to the sealed vial. Then draw out 99ml's (20ml's at a time, or whatever size syringe you're working with) and filter it through the filter in to the vial as well.
You have yourself Bacteriostatic Water.