Accessories
Bacteriostatic Water
10ml
Sterile water with 0.9% benzyl alcohol. For peptide reconstitution.
Sterile · Batch UKPL-818
- Same-day dispatch before 2pm, Mon to Fri
- Add £64.01 more for free UK delivery
- Cold-chain shipping. Always. Dry-cold pack, Royal Mail Tracked 24
- Lost, damaged or wrong? Replaced free if you tell us within 48 hours.
- Research use only. For in-vitro laboratory research. Not for use in humans or animals, or in food, drugs or diagnostics. Not evaluated by the MHRA or FDA. The buyer is responsible for handling and regulatory compliance.
What is Bacteriostatic Water?
Bacteriostatic water, or bac water, is sterile water with 0.9% benzyl alcohol as a preservative. It is the standard diluent for reconstituting lyophilised research peptides. Each vial holds 10ml.
Full description
The benzyl alcohol, 9mg per ml or 90mg per vial, holds back microbial growth between withdrawals. That lets one vial serve several reconstitutions within its in-use period. Benzyl alcohol and phenol are the two most common preservatives in licensed peptide and protein products (Meyer et al., J Pharm Sci, 2007).
Bacteriostatic Water Research Applications
Any lab working with lyophilised peptides needs a diluent to bring them into solution before in-vitro work. One 10ml vial covers several reconstitutions, for example of BPC-157, TB-500, MOTS-C, ipamorelin or DSIP.
Bacteriostatic Water vs Sterile Water for Injection
Sterile water for injection has no preservative. Once its seal is broken, nothing holds back organisms carried in on a needle, so it is a single-use diluent. Bacteriostatic water adds 0.9% benzyl alcohol, so one vial can be entered repeatedly for 28 days after first puncture. Choose sterile water when the preservative must be kept out of a design. Meyer and colleagues (2007) list a preservative's effect on the active ingredient among the main criteria for choosing one.
Research Overview
Bacteriostatic water is sterile water containing 0.9% (9 mg/mL) benzyl alcohol as a bacteriostatic preservative, and it is the standard laboratory diluent for reconstituting lyophilised research peptides. Commonly shortened to bac water, it corresponds to the pharmacopoeial article Bacteriostatic Water for Injection, USP, and is distinguished from Sterile Water for Injection by that preservative alone. Sterile Water for Injection contains no bacteriostat, antimicrobial agent or added buffer, which is why it is presented as a single-use article; bacteriostatic water is presented as a multiple-dose container precisely because the benzyl alcohol permits repeated withdrawals from one vial. Benzyl alcohol is an aromatic alcohol that acts on microbial membrane integrity and permeability. Critically, it is bacteriostatic rather than bactericidal: it suppresses proliferation of organisms introduced at the septum during needle entry, it does not sterilise a solution that is already contaminated. That distinction drives handling practice, because bacteriostatic water does not rescue a compromised vial and is no substitute for aseptic technique. The pharmacopoeial article is supplied sterile and non-pyrogenic with a typical pH of 5.7 against a specified range of 4.5 to 7.0, and is held at controlled room temperature. In a peptide laboratory it is the highest-turnover consumable in the workflow, since lyophilised material must be brought into aqueous solution before any analytical or in-vitro work can begin, and the preservative lets a single 10ml vial serve multiple reconstitution sessions across a working period. Because preservative effectiveness is only required to be demonstrated for 28 days after first entry, standard multiple-dose vial practice, reflected in CDC injection safety guidance, is to date the vial at first puncture and discard it 28 days later. For laboratories sourcing bacteriostatic water UK side, the specifications worth confirming are sterility, benzyl alcohol concentration and fill volume. Supplied for research use only.
Product Specifications
- Composition
- Sterile water with 0.9% (9mg/ml) benzyl alcohol
- Preservative
- Benzyl alcohol, bacteriostatic
- Volume
- 10ml
- Purity
- Sterile
- Batch
- UKPL-818
- Appearance
- Clear, colourless solution
- Storage
- 20-25°C, away from direct light, do not freeze
- In-Use Period
- Date at first puncture, discard after 28 days
- Form
- Ready-to-use solution, no reconstitution required
Storage and Handling
Store unopened vials at 20-25°C, away from direct light. Do not freeze. Write the date on the vial at first puncture and discard it 28 days later, or at the printed expiry if that comes first. Discard any vial that is cloudy, has particles or has a damaged seal.
How to handle
Bacteriostatic water needs no preparation. Swab the stopper with alcohol and let it dry before each entry. Add it slowly down the inside wall of the peptide vial, not onto the powder, and swirl gently until dissolved.
- Bacteriostatic water requires no preparation. Swab the stopper with 70% isopropyl alcohol before every needle entry and allow it to dry before piercing.
- Use a fresh sterile needle and syringe for each withdrawal, and never return withdrawn solution to the vial.
- Date the vial at first puncture and discard 28 days later in line with standard multiple-dose vial practice. Never use beyond the printed expiry, regardless of the in-use date.
- Store at controlled room temperature, 20-25°C, protected from direct light. Do not freeze.
- Inspect before every use. Discard the vial if the solution is not clear and colourless, if particulates are visible, or if seal or stopper integrity is in any doubt.
- Remember that the preservative is bacteriostatic, not sterilising. It suppresses growth of organisms introduced during needle entry and does not decontaminate a vial that has already been compromised.
- The site reconstitution guide and reconstitution calculator cover the aseptic workflow and dilution arithmetic for lyophilised peptides.
To mix a peptide, see the peptide reconstitution guide and the reconstitution calculator.
Research References
Bacteriostatic Water Price (UK)
Bacteriostatic Water 10ml is for sale at £4.99 per vial, supplied from stock in the UK. UK delivery is £4.50 by Royal Mail Tracked 24, free over £69.
| Vial | Price | Availability |
|---|---|---|
| Bacteriostatic Water 10mlThis page | £4.99 | In stock |
Prices are in GBP per vial of ready-to-use solution and match the basket. See the FAQ for delivery and payment options, and quality & testing for how each batch is checked.
Frequently Asked Questions
What is the difference between bacteriostatic water and sterile water?
The difference is the preservative: bacteriostatic water contains 0.9% benzyl alcohol, sterile water contains none. Sterile Water for Injection, USP is specified as containing no bacteriostat, antimicrobial agent or added buffer, so once its seal is broken there is nothing suppressing microbial growth and it is treated as a single-use article. Bacteriostatic water can be entered repeatedly over a defined in-use period because the benzyl alcohol keeps introduced organisms from proliferating.
How long does bacteriostatic water last once opened?
Standard practice is to discard bacteriostatic water 28 days after first puncture. Manufacturers are only required to demonstrate that the bacteriostatic agent remains effective for 28 days after initial entry, and CDC multiple-dose vial guidance reflects this by directing that an opened vial be dated and discarded within 28 days unless the manufacturer states otherwise. Mark the date of first puncture on the vial, and never exceed the printed expiry even if the 28 days have not elapsed.
Why is bac water used to reconstitute peptides?
Bac water is used because lyophilised peptides have to be dissolved in an aqueous vehicle before any analytical or in-vitro work, and the benzyl alcohol allows one vial of diluent to serve several reconstitution sessions without microbial proliferation between entries. Plain sterile water would have to be discarded after a single entry, which is impractical for a laboratory reconstituting multiple compounds over a working period.
Does bacteriostatic water sterilise a contaminated vial?
No. Benzyl alcohol is bacteriostatic, meaning it inhibits the multiplication of organisms, not bactericidal, meaning it does not kill an established population. It suppresses growth of small numbers of organisms introduced at the septum during needle entry, but it will not decontaminate a solution or vial that has already been compromised. Aseptic technique remains the control, and any vial of questionable integrity should be discarded.
How should bacteriostatic water be stored?
Store bacteriostatic water at controlled room temperature, 20-25°C, protected from direct light, and do not freeze. Refrigeration is not required, since the preservative rather than cold storage is what maintains the in-use period. Keep the stopper clean, swab it with 70% isopropyl alcohol before each needle entry, and record the first-puncture date on the label.
How much benzyl alcohol is in a 10ml bacteriostatic water vial?
A 10ml vial at 0.9% benzyl alcohol contains 90 mg of benzyl alcohol in total, since 0.9% corresponds to 9 mg/mL. That 0.9% figure is the concentration specified for the Bacteriostatic Water for Injection, USP article and is the concentration standard across peptide research laboratories.
Can bacteriostatic water be frozen?
No, bacteriostatic water should not be frozen. Freezing provides no stability benefit, as the benzyl alcohol rather than temperature is what maintains the in-use period, and freeze-thaw cycling stresses the closure and stopper, which is exactly the barrier the preservative depends on. Hold vials at controlled room temperature, 20-25°C, instead.
Where can I buy bacteriostatic water in the UK?
UK Peptide Lab supplies sterile bacteriostatic water in 10ml vials, 0.9% benzyl alcohol, current batch UKPL-818, with same-day UK dispatch on orders placed before 2pm UK time and free UK Royal Mail Tracked shipping over £69. It is our highest-attach consumable because every lyophilised peptide needs a diluent. Supplied for research use only, buyers must be 18 or over.
Is bacteriostatic water UK legal to buy for research?
Yes, for laboratory research. We sell it for research use only, to buyers aged 18 or over. It is not supplied as a medicine.
What size are your bac water vials and how long do they last?
Each vial holds 10ml. Unopened, use it before the printed expiry. Once pierced, discard it 28 days after first puncture.
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