Titus Thorne

Last Updated March 13, 2023

Titus Thorne

 March 13, 2023

Curious about Bacteriostatic Water vs. Sterile Water?

Then you're in luck, as below we breakdown why Bacteriostatic water is a must-have for researchers and laboratory professionals.

The sterile solution is used to perform safe injections of various therapeutic substances, such as peptides and hormones.

It is made with a gentle organic preservative that keeps it sterile to prevent infection and prolong its shelf life. This preservative sets bacteriostatic water apart from plain sterile water, another solution formulated for medical use.

In this guide, we will explore:

  • Similarities
  • Differences
  • Compositions
  • Usage
  • Proper storage

This will help you choose the best one for your needs. Keep reading to figure out which one is your best choice!

Buy Bacteriostatic Water from our #1 recommended vendor...

Disclaimer: Peptides.org contains information about products that are intended for laboratory and research use only, unless otherwise explicitly stated. This information, including any referenced scientific or clinical research, is made available for educational purposes only. Peptides.org makes every effort to ensure that any information it shares complies with national and international standards for clinical trial information and is committed to the timely disclosure of the design and results of all interventional clinical studies for innovative treatments publicly available or that may be made available. However, research is not considered conclusive. Peptides.org makes no claims that any products referenced can cure, treat or prevent any conditions, including any conditions referenced on its website or in print materials.

What is Bacteriostatic Water?

If you are a peptide researcher, you have probably come across bacteriostatic water. It is a sterile solution of water and benzyl alcohol, a bacteriostat molecule that is organically derived. The 0.9% benzyl alcohol content impedes microbial growth and contamination [1].

Bacteriostatic water is intended as a dilutant or solvent for preparations that require dissolution before hypodermic injection [1, 2]. The United States Pharmacopeia (USP) substance has a pH level of 4.5 to 7.0 and is widely available for use in various contexts, including medical centers and research laboratories [3].

Bacteriostatic water is a favorite solvent due to its preservative content, which allows multiple doses to be sourced from a single vial without contamination. It remains sterile for up to 28 days after the first dose, extending the shelf life of its preparations. If unused, a vial may remain sterile for several years[4].

Though popular, bacteriostatic water is not ideal for all populations, such as newborns and those with benzyl alcohol allergies. It may also interact with certain medications, so handlers should closely adhere to manufacturer indications [4, 5].

Bacteriostatic Water

What is Bacteriostatic Water Used For?

Bacteriostatic water is widely used as a solvent or dilutant for therapeutic substances or medications indicated for aqueous injection. More specifically, it is applied in the following contexts [4]:

  • To dilute a liquid in order to achieve the indicated concentration required for injection.
  • As a solvent to reconstitute lyophilized substances, such as peptides, hormones, and medications, enabling injection.

Its 0.9% benzyl alcohol content serves as a bacteriostat agent to combat microbial contamination and the risk of infection. As such, a single vial of the solvent can safely provide multiple doses and remains viable for up to four weeks after the first dose.

Solutions made with bacteriostatic water also have extended shelf life. The sterility of bacteriostatic water is crucial in research contexts, as performing injections with contaminated materials can lead to grave infection [4].

Bacteriostatic water is a popular solvent due not only to its preservative content, but its efficiency and minimal interaction with many peptides and hormones [6, 7]. It is suited to most parenteral injection routes, including intravenous, intramuscular, and subcutaneous. [1]:

There are several precautions to keep in mind. Handlers are instructed to avoid the use of this solvent in intrathecal injections, as well as in neonate subjects. [2, 8]. Additionally, bacteriostatic water is dangerous when injected alone without a solute.

The injection of pure bacteriostatic water is also linked to hemolysis, a dangerous condition of red blood cell degeneration [9, 10]. There have been rare instances of adverse effects, including the development of abscesses at injection sites, blood clots, and fever [9].

What is Sterile Water?

Sterile water is purified and distilled water that is free of pathogens. It has no antimicrobial agents or preservatives and is available in single-dose containers to prevent contamination and infection.

There are several different formulations designated by the USP for distinct uses, namely Sterile Water for Injection and Sterile Water for Irrigation. As their names suggest, the former is indicated for use in injections, while the latter is used for purposes such as rinsing wounds. They are not interchangeable, as Sterile Water for Injection is subject to particulate matter tests, while Sterile Water for Irrigation is not [5, 11].

In its injection capacity, sterile water acts as a solvent or dilutant of medications or therapeutic substances, much like bacteriostatic water. It has a pH level of 5.0-7.0, averaging a pH of 5.5. Sterile water is considered more difficult to produce than bacteriostatic water and is in shorter supply [5, 11]. The complex disinfection procedure involved in producing sterile water features [12]:

  • A pre-filtration process that includes deionization, dechlorination, UV disinfection, and reverse osmosis.
  • Distillation using multiple methods, such as vapor compression.
  • Following this, strict protocols are implemented to ensure that the water does not become contaminated.

As a solvent or dilutant, sterile water is most often mixed with lyophilized powders for the reconstitution of medications, therapeutic peptides, and hormones. It is suitable for injections via intravenous, intramuscular, or subcutaneous routes.

Contraindications include injection without a solute, as this can cause hemolysis. Additionally, it is not recommended for subjects on certain medications. Adverse reactions are rare but can occur, and it is not for use in cerebrospinal injections [13, 14].

Bacteriostatic Water

What is Sterile Water Used for?

Sterile water is used to dilute or dissolve substances that require aqueous suspension for injection. The use of uncontaminated solvents for injections is crucial to avoiding infection. Further, it is important to select pharmacological-grade solutions, as those produced in unregulated conditions can easily become contaminated [4].

Because it does not have a preservative or bacteriostat agent, sterile water can become contaminated upon contact. Thus, it is sold in single-dose vials. Solutions made with sterile water are subject to contamination and rapid degradation even if they are refrigerated.

The United States Food and Drug Administration states that sterile water preparations should be discarded after four hours [15]. For this reason, it is not always the best option for reconstitution. However, it is suitable for single-use doses, as well as individuals who may be allergic to the benzyl alcohol in bacteriostatic water. Further, some drugs are indicated for use with only sterile water.

Sterile water is used not only in medication injections, but in the reconstitution of therapeutic compounds, including:


Sterile water is a popular solvent for peptides, as it does not interfere with peptide purity. It also enables reconstituted peptides to be lyophilized without residue [16].


Sterile water is also used to inject therapeutic hormones, such as HGH and HCG. However, solutions made with sterile water should be immediately discarded after one use, according to the FDA [15, 17].

Injection routes for sterile water solutions include [13]:

  • Intramuscular injection
  • Intravenous injection
  • Subcutaneous injection

It is strictly advised to discard sterile water containers after one use.

Bacteriostatic Water vs. Sterile Water

Now it’s time to weigh the similarities and differences between bacteriostatic water and sterile water. Both sterile solvents for injections in a range of contexts, these two substances certainly overlap in many areas.

However, there are also several significant differences between them. Let’s take a look at their shared and distinct features [5].


Sterile water and bacteriostatic water have these features in common [5]:

1. Formulations

  • They are sterile solutions intended for use in medical injections.
  • Both are made with sterile water; bacteriostatic water consists of sterile water plus benzyl alcohol.
  • They have similar pH levels, averaging pH 5.5 (sterile water) and pH 5.7 (bacteriostatic water).
  • Both are manufactured in regulated environments per US Pharmacopeia (USP) standards and are considered pharmaceutical grade.

2. Uses

  • Their uses overlap, as both sterile water and bacteriostatic water are applied as dilutants or solvents of medications before injection.
  • They are often used to reconstitute common solutes from lyophilized powders, including peptides, hormones, and various medications.
  • Both are suitable for intravenous injections, subcutaneous injections, and intramuscular injections.

3. Precautions

  • Precautions to maintain sterility are required when using both. If contamination occurs, they are no longer suitable for use.
  • Neither should be administered without a well-mixed solute. Injecting bacteriostatic water or sterile water alone can lead to hemolysis.
  • Both substances are contraindicated for use in cerebrospinal injections and subjects taking certain medications.


Now, let’s explore their differences in their formulations, uses, and precautions [5]:

1. Formulations

  • Although similar, these two substances are chemically distinct. Bacteriostatic water features an organic bacteriostat (0.9% benzyl alcohol) to prevent contamination, while sterile water has no added preservatives. While bacteriostatic water has a pH level of 4.5-7.0, the pH level of sterile water is 5.0-7.0.
  • Bacteriostatic water is considered easier to produce and is more readily available. Sterile water has been in short supply for years due to supply chain issues, and the recent COVID-19 pandemic has worsened this issue [11, 18, 19].
  • Bacteriostatic water tends to provide better solubility due to its alcohol content [6].

2. Uses

  • Because it has no additives, sterile water is considered contaminated with one use. So, it is sold in single-dose containers that are strictly forbidden for re-use. Meanwhile, bacteriostatic water remains uncontaminated for up to 28 days through multiple uses and is available in multi-dose vials [4, 5].
  • For this reason, reconstitutions made with bacteriostatic water remain usable for longer than those made with sterile water. For example, specialists advise that HGH reconstituted with bacteriostatic water may be refrigerated and used within two to four weeks, while those made with sterile water should be immediately discarded after one use [15, 20].

3. Precautions

  • Bacteriostatic water is not suitable for newborns or subjects that are allergic to benzyl alcohol.
  • Sterile water and bacteriostatic water may interact with certain drugs. Thus, they may have different indications and are not interchangeable.

Bacteriostatic Water

Which Product is Best?

Weighing key factors such as convenience, cost, efficiency, and safety, it is clear that bacteriostatic water is the best option.

Its organic bacteriostat agent not only decreases the risk of infection from contamination, but bacteriostatic water solutions last longer and are available in multi-dose vials, saving time and money. Multiple doses can be drawn from a single vial, and peptides reconstituted with bacteriostatic water can remain viable for weeks with proper storage. In contrast, sterile water vials are only good for single doses, and solutions made with sterile water cannot be stored [6].

Plus, specialists agree that bacteriostatic water is a more effective solvent, especially for therapeutic peptides. Proper mixing is crucial to peptide safety and efficacy. Experts advise that bacteriostatic water is the first choice in this regard, as it dissolves most peptides and does not interfere with their potency [6, 16, 21].

Additionally, when reconstituting peptides, it is recommended practice to first prepare a highly concentrated stock solution and then dilute further as necessary. If this is done with bacteriostatic water, the stock solution can be stored for future use. However, sterile water reconstitutions bar this method, as they must be immediately used or discarded [16].

Note that sterile water may be the better choice with certain medications, substances, or recipient conditions. This includes, for instance, subjects that are allergic to benzyl alcohol. So, it is important to always observe manufacturer labels and medical instructions.

While sterile water and bacteriostatic water fulfill many of the same functions, the benefits of bacteriostatic water outweigh the alternative in most cases.

Where to Buy Bacteriostatic Water Online?

If you are interested in adding bacteriostatic water to your toolkit but are unsure where to start, don’t worry! We have surveyed the internet and selected your top online source.

To safely use bacteriostatic water, specialists unanimously recommend several complementary items such as alcohol swabs, sterile syringes, and sterile needles. The prospect of buying all of these items from multiple sources sounds like a headache, especially considering the many unvetted manufacturers online.

Luckily, the Peptides.org team has identified a trusted online retailer that is a one stop shop for all your research supply requirements:


This excellent source offers the best research tools in efficient packages, saving you the hassle of combing the market for all you need. Its premium selection includes two top-notch research kits.

Here are the starter kit items:

  • 200 Alcohol Prep Pads
  • 1 Sterile Empty Glass Vial (10mL)
  • 3 vials of Bacteriostatic Water (30mL)
  • 10 Large Needles + Syringes Combo (3cc x 21g x 1)
  • 100 Insulin Syringes (0.5 cc/mL x 29g x ½)

If you want a little more, check out the premium kit:

  • 200 Alcohol Prep Pads
  • 2 Sterile Empty Glass Vials (10mL)
  • 5 vials of Bacteriostatic Water (30mL)
  • 20 Large Needles + Syringes Combo (3cc x 21g x 1)
  • 200 Insulin Syringes (0.5 cc/mL x 29g x ½)

You couldn’t ask for a better research material supplier.

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Sterile Water vs. Bacteriostatic Water | Verdict

Sterile water and bacteriostatic water are both useful solvents for safely performing injections.

However, bacteriostatic water is the clear winner for the greater number of benefits it delivers. Featuring an organic preservative, bacteriostatic water resists contamination to supply multiple doses and extended shelf life. Plus, it is a more efficient solvent.

For these reasons, bacteriostatic water is the preferred option among researchers for the safe and easy injection of therapeutic compounds and medications.

If you’re a licensed researcher or laboratory professional, find all you need to get started at bacteriostaticwater.org.


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  2. Bacteriostatic Water for Injection [Internet]. Drugs.com. 2021 [cited 2022Aug17]. Available from: https://www.drugs.com/pro/bacteriostatic-water-for-injection.html
  3. Jackson S. The complete guide on Bacteriostatic Water [Internet]. MedLab International. MedLab International; 2019 [cited 2022Aug17]. Available from: https://medlabgear.com/blogs/articles/guide-bacteriostatic-water
  4. The uses of bacteriostatic water and where to get it [Internet]. Farris Laboratories, Inc. Farris Laboratories, Inc.; 2021 [cited 2022Aug17]. Available from: https://www.farrislabs.com/blogs/information/the-uses-of-bacteriostatic-water-and-where-to-get-it
  5. Bacteriostatic water vs. Sterile Water: The differences that Can save your life [Internet]. Bacteriostaticwater.com. 2020 [cited 2022Aug17]. Available from: https://www.bacteriostaticwater.com/blogs/news/bacteriostatic-water-vs-sterile-water-the-differences-that-can-save-your-life
  6. Deusmedical. Bacteriostatic water vs. Sterile Water  [Internet]. DeusMedical.com. [cited 2022Aug17]. Available from: https://deusmedical.com/articles/which-one-to-choose-bacteriostatic-water-vs-sterile-water
  7. Hawkins M. 3 facts you need to know about bacteriostatic water: Performance forum [Internet]. Performance Forum | Join The Debate. 2019 [cited 2022Aug18]. Available from: https://www.performanceforum.org/3-facts-you-need-to-know-about-bacteriostatic-water/
  8. Feasby TE, Hahn AF, Gilbert JJ. Neurotoxicity of bacteriostatic water. N Engl J Med. 1983 Apr 21;308(16):966-7. doi: 10.1056/NEJM198304213081614. PMID: 6687625.
  9. Bacteriostatic water for injection, USP warnings and precautions [Internet]. bacteriostatic water for injection, USP Warnings and Precautions | Pfizer Medical Information – US. 2022 [cited 2022Aug18]. Available from: https://www.pfizermedicalinformation.com/en-us/node/657396/pi_section/field_spl_warnings
  10. Rapido F. The potential adverse effects of haemolysis. Blood Transfus. 2017 May;15(3):218-221. doi: 10.2450/2017.0311-16. PMID: 28518048; PMCID: PMC5448827.
  11. Sterile Water For Injection Shortage FAQ [Internet]. ASHP. 2018 [cited 2022Aug23]. Available from: https://www.ashp.org/drug-shortages/shortage-resources/sterile-water-for-injection-faq?loginreturnUrl=SSOCheckOnly#
  12. What is water for injection? [Internet]. Technical Safety Services LLC. 2021 [cited 2022Aug23]. Available from: https://techsafety.com/blog/what-is-water-for-injection
  13. Sterile Water for Injection, USP [Internet]. STERILE WATER (sterile water for injection, USP) | Pfizer Medical Information – US. 2022 [cited 2022Aug23]. Available from: https://www.pfizermedicalinformation.com/en-us/sterile-water
  14. Dwivedi D, Ray A, Singh S, Sud S, Hooda B. Inadvertent sterile water injection in the epidural space: history revisited. Korean J Anesthesiol. 2020 Dec;73(6):562-563. doi: 10.4097/kja.19100. Epub 2019 Jun 4. PMID: 31159538; PMCID: PMC7714630.
  15. Sterile water for injection, USP – Food and Drug Administration [Internet]. [cited 2022Aug24]. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/018632s051lbl.pdf
  16. Peptide Information. Peptide reconstitution [Internet]. Peptide Information. 2019 [cited 2022Aug18]. Available from: https://www.peptidesciences.com/information/peptide-reconstitution/
  17. Human chorionic gonadotropin, HCG injection [Internet]. Cleveland Clinic. 2022 [cited 2022Aug18]. Available from: https://my.clevelandclinic.org/health/drugs/18559-human-chorionic-gonadotropin-hcg-injection
  18. Anderson M. Pandemic spurring hospital shortage of pipette tips, sterile water, analysis finds [Internet]. Becker's Hospital Review. 2021 [cited 2022Aug24]. Available from: https://www.beckershospitalreview.com/supply-chain/pandemic-spurring-hospital-shortage-of-pipette-tips-sterile-water-analysis-finds.html
  19. Fluid shortages: Current challenges in accessing a staple supply [Internet]. Premier. 2022 [cited 2022Aug24]. Available from: https://premierinc.com/newsroom/blog/fluid-shortages-current-challenges-in-accessing-a-staple-supply
  20. Abernathy DS. How to mix and store HGH: Best water for mixing HGH [Internet]. HRTGuru. 2022 [cited 2022Aug24]. Available from: https://hrtguru.com/water-to-mix-hgh/
  21. Jodynesbitt. Which one to pick bacteriostatic water vs sterile water ? [Internet]. Buy Direct Peptides Online. 2018 [cited 2022Aug24]. Available from: https://direct-peptides.com/bacteriostatic-water-vs-sterile-water/#:~:text=Which%20is%20better%3F,best%20to%20use%20bacteriostatic%20water.

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