The Complete Guide on Bacteriostatic Water
Bacteriostatic water is both a bacteriostatic agent and a key ingredient in laboratories, hospitals, and research centers around the world.  Bacteriostatic agents have been used for as long as modern medicine has been practiced.  These agents are used to prevent the growth of bacteria in different formulas, canisters, containers, and utensils.  Bacteriostatic agents, including bacteriostatic water, stop bacteria reproduction but they don’t typically kill off bacteria that have already taken root.  

Benzyl Alcohol Based, Designed for Injection Mixes

Bacteriostatic water for injection contains 0.9% of benzyl alcohol as a bacteriostatic preservative.  Benzyl alcohol is naturally made by plants and is found in fruit and tea leaves.  Completely safe to use, benzyl alcohol is ideal for the composition of bacteriostatic water because of its low toxicity, low vapor pressure, and pleasant odor.  The benzyl alcohol ensures the bacteriostatic water has an acceptable pH level ranging between 4.5 to 7.0, but averaging out at 5.7.  The unique characteristics of benzyl alcohol that provide a unique balance between pleasantries and efficacies are what allows bacteriostatic water to be the ideal substance used for medication dilution prior to injection.  

3 Precautions to Remember

While benzyl alcohol and its use in bacteriostatic water are presumed to be safe, there are some precautionary rules that we need to consider to responsibly use the solution.  Manufacturers and supplying companies like us here at Med Lab Gear will often dictate very specific instructions and warnings regarding bacteriostatic water and its use.  As a general rule though, there are 3 precautions that should be considered regardless of manufacturing company or distributing organization:
  1. Toxic agent in newborn children[i] – Since 1983, we’ve known that benzyl alcohol can cause serious problems in young children. The report published by the American Academy of Pediatrics says that introducing benzyl alcohol “caused severe metabolic acidosis, encephalopathy, respiratory depression with gasping, and perhaps other abnormalities leading to the death.”  Since then, the Food and Drug Administration has put a blanket ban on the use of benzyl alcohol and benzyl alcohol-based products like bacteriostatic water in neonatal units around the United States.
  2. Causes problems in pregnancy – It makes sense that because infants are poisoned by the benzyl alcohol in bacteriostatic water, so too are fetuses. The benzyl alcohol can cause fetal harm in a pregnant woman, leading to eventual deformities, mental disabilities, physical disabilities, or even death.  The younger the unborn child, the more problematic the bacteriostatic used in medication would be.
  3. Adverse effects when combined with certain drugs or solutions – While bacteriostatic water is perfect for diluting most medications, it certainly doesn’t play well with everything out on the market. It’s best to consider what other medications are going to be in a patient’s bloodstream before giving a bacteriostatic water-rich injection.  Consulting with a pharmacist, other doctors, or the FDA is suggested before mixing medications.

How to Administer Bacteriostatic Water

Properly utilizing the bacteriostatic water is key, otherwise you’re just wasting your money.  How you utilize the bacteriostatic water is going to be dictated by what you are using the solution for.  If you’re working on a developmental project in a research laboratory, for instance, you will not be using the bacteriostatic water in the same manner as you would be if you’re working in a hospital or doctor’s office, administering FDA approved injected medications for treatment. Individuals working in a research laboratory/clinical data collection setting – Rather than using a syringe with a needle, you will need a pipette.  Be sure all utensils are sterile and never before used so that you don’t accidentally contaminate your works!
  • Gently squeeze the pipette’s bulb before inserting the pipette tip into the bacteriostatic water.
  • Gently insert the pipet tip into the bacteriostatic water.
  • Very slowly relax your grip on the pipette’s bulb until the solution reaches the desired level visible in the pipette tip.
  • Slowly bring the pipette tip out of the water while keeping a relaxed grip on the pipette’s bulb.
  • Put the pipette’s tip into the destination vial/bottle’s mouth and slowly expel the bacteriostatic water. (Do not expel the water too quickly; Air bubbles are bad!)
  • Remove the pipette tip and discard or place it in the sterilization chamber.
Individuals working in a hospital or doctor’s clinic, doling out injections of FDA approved medications – Rather than using a pipette, you will need a syringe and needle.  Be sure all utensils are sterile and never before used so that you don’t accidentally cause infection or spread blood bourn diseases to your patients!
  • Carefully install the needle tip on to the syringe of your choosing.
  • Insert the needle tip into the sealed bottle of bacteriostatic water.
  • Slowly extract the bacteriostatic water until the solution reaches the desired level visible in the syringe body.
  • Gently remove the needle from the bacteriostatic water vial.
  • Penetrate the medication’s vial, as gently as you can.
  • Dispel the solution into the vial, taking care to push it against the side of the vial.
  • Remove your freshly contaminated needle and replace it with another sterilized one.
  • Slowly extract the medication/bacteriostatic water mix until the solution reaches the desired level visible in the syringe body.
  • Carefully perform your injection on a disinfected and prepped area of the patient’s body as you normally would. Discard both needles and the syringe after use!

Storage Rules for Bacteriostatic Water

Whether your bacteriostatic water vials come with rubber stoppers or flip top lids, the storage rules should largely remain the same.  If your vial has been opened, you should make sure to use the water within a month.  Do not risk using it beyond that because the benzyl alcohol loses its potency and bacteria will be able to continue to thrive inside the vial.  There are no special rules that need to be followed as far as discard. Keep your unused bacteriostatic water in the container it arrives in.  Store the container in a dark place with a residual, resting room temperature that doesn’t exceed 80 degrees Fahrenheit and doesn’t drop below 60 degrees Fahrenheit.  Keeping the water in the dark and the temperature at the specified range will keep the benzyl alcohol from diluting faster than usual, extending the shelf life of your unopened bacteriostatic water vials for months to years. NOTE: Do not stack anything on top of the bacteriostatic water vials.  Stacking will cause the lids or vial bodies to weaken and can cause unexpected cracks and leaks.  

Transportation Guidelines for Bacteriostatic Water

When transporting your bacteriostatic water from location to location in your lab, remember to keep two hands on the container.  If you’re transporting just a single vial, grasp the vial tightly in your hand so you don’t risk drop. When transporting your bacteriostatic water from location A to location B, miles away, take care to follow all the same storage rules you would if the water were waiting to be used inside your clinic or lab.  Make sure nothing is stacked on top of the vials and provide some extra padding, if necessary, to prevent unwanted breaks.  

Side Effects of Bacteriostatic Water Usage

Apart from the very rare allergic reaction, there are a few potential side effects that you need to consider.  Local tenderness at an injection site can be caused by the benzyl alcohol in the bacteriostatic water.  We already know how serious exposure can be to a fetus but there is little concern for an adult human.  Unfortunately, several animals aren’t quite as lucky.  Much like a human infant or fetus, smaller animals suffer from all the same toxic effects.  Consider using sterile water as a substitute for animals and infants.  

Med Lab Gear Bacteriostatic Water

Our bacteriostatic water is packaged in semi-rigid vials that are created specifically for laboratory solutions like bacteriostatic water.  The container doesn’t need a vapor barrier to keep the labeled volume.  We use the industry standard .9% benzyl alcohol as the active bacteriostatic preservative and aim to keep the pH at 5.7 to ensure consistency and efficacy. NOTE: Med Lab Gear only distributes bacteriostatic water in 30ml vials.  

Bacteriostatic Water vs. Sterile Water

Do not confuse the two, as bacteriostatic water is not the same as sterile water.  Sterile water comes with no microbes at all so it can be more pricey than bacteriostatic water.  Sterile water is manufactured and distributed for single-use only.  The sterile water is only sterile until it has been opened.  The moment air hits the liquid, it’s considered contaminated.  The same goes for inserting an instrument or utensil inside. Bacteriostatic water is designed for reuse.  With bacteriostatic water, it generally doesn’t matter if a utensil, instrument, or air hit the water as the bacteriostatic agent or preservative inside the water, most commonly benzyl alcohol, prevents the growth of bacteria or fungi. NOTE: Bacteria, viruses, or fungi can be in the bacteriostatic water once you’ve used it.  If that’s a problem, you need sterile water instead. [i] Gershanik, Brown. “Benzyl Alcohol: Toxic Agent in Neonatal Units.” Pediatrics, American Academy of Pediatrics, 1 Sept. 1983,