How much bacteriostatic water do I add to a peptide vial?

It depends on the desired concentration. A common approach for a 5mg vial is 2ml BAC water, yielding 2,500 mcg/ml. For a 10mg vial, 2ml yields 5,000 mcg/ml.

How long is reconstituted peptide stable?

Reconstituted with bacteriostatic water, most peptides are stable for up to 28 days refrigerated. Reconstituted with plain sterile water (no preservative), stability drops to approximately 24 hours.

How to Reconstitute Peptides with Bacteriostatic Water (2026)

What Is Bacteriostatic Water?

Bacteriostatic water (BAC water) is sterile water for injection containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth in multi-use vials, extending the stability of reconstituted peptides to approximately 28 days refrigerated.

Plain sterile water has no preservative and drops stability to roughly 24 hours after reconstitution — making BAC water the strongly preferred solvent for research peptide reconstitution unless same-day use is planned.

💧 BAC Water vs. Sterile Water

Bacteriostatic water: Contains 0.9% benzyl alcohol preservative → 28 days stability refrigerated
Sterile water (no preservative): No antimicrobial protection → 24 hours stability
Recommendation: Always use bacteriostatic water for research reconstitution unless explicitly contraindicated by the compound

Supplies Needed

Lyophilized peptide vial
Bacteriostatic water vial (Evo Peptides 30ml)
Insulin syringe (U-100, 0.5ml or 1ml, 28–29 gauge)
Alcohol swabs (×2 minimum per reconstitution)
Permanent marker for labeling
Refrigerator for storage

Step-by-Step Reconstitution

1
Wash hands thoroughly
Clean technique is essential. Wash with soap for at least 20 seconds before handling any vials or syringes.
2
Wipe both vial tops with alcohol swabs
Swab the rubber stopper of both the peptide vial and the BAC water vial. Allow to air dry for 10–15 seconds before inserting any needle.
3
Calculate and draw your BAC water volume
Determine your target concentration (see calculator below), then draw the corresponding volume of BAC water into your syringe. Pull back slightly more than needed, then push to exact volume to remove air bubbles.
4
Insert needle and inject slowly down the vial wall
Critical step: Insert the needle at an angle so the BAC water runs slowly down the inner glass wall — never inject directly onto the powder. Direct forceful injection can denature the peptide.
5
Swirl gently — do not shake
Rotate the vial gently between your fingers or roll it on a flat surface. The powder should dissolve within 30–60 seconds, yielding a clear, colorless solution. Shaking creates bubbles and can denature peptides.
6
Inspect the solution
The reconstituted solution should be clear and colorless (exception: GHK-Cu will be blue due to its copper content). Cloudiness or particulates may indicate contamination or degradation — do not use.
7
Label and refrigerate immediately
Mark the vial with the peptide name, concentration (mcg/ml), and reconstitution date. Refrigerate at 2–8°C. Do not freeze a reconstituted vial. Use within 28 days.

Concentration Calculator

Use this reference table to determine the resulting concentration based on vial size and BAC water volume added:

5mg Vial Concentrations

1ml

BAC Water → 5,000 mcg/ml

2ml

BAC Water → 2,500 mcg/ml

5ml

BAC Water → 1,000 mcg/ml

10mg Vial Concentrations

1ml

BAC Water → 10,000 mcg/ml

2ml

BAC Water → 5,000 mcg/ml

5ml

BAC Water → 2,000 mcg/ml

Common Mistakes to Avoid

⚠️ Most Common Errors

Injecting directly onto powder — Always aim BAC water at the inner vial wall, not the powder cake
Shaking the vial — Shaking can denature the peptide and creates difficult-to-clear air bubbles
Using plain sterile water — Without the bacteriostatic preservative, stability drops to 24 hours
Freezing reconstituted peptide — Freeze only lyophilized (unreconstituted) vials; freezing liquid solution degrades most peptides
Not labeling with date — 28-day stability window is easy to lose track of without a clear date
Using a dull or used needle — Always use a fresh syringe; reused needles are not suitable for research applications

Storage After Reconstitution

State	Storage	Stability
Lyophilized powder (sealed)	Refrigerated 2–8°C	Months to years (check COA)
Reconstituted with BAC water	Refrigerated 2–8°C, do not freeze	Up to 28 days
Reconstituted with sterile water	Refrigerated 2–8°C	~24 hours
Lyophilized powder (long-term)	Freezer −20°C (sealed)	1–2 years or longer

Frequently Asked Questions

How much BAC water should I add to a peptide vial?

It depends on your desired working concentration. The most common approach is 2ml per 5mg vial, yielding 2,500 mcg/ml. This gives convenient unit math: 0.1ml (10 units on a U-100 syringe) = 250 mcg.

Can I reconstitute multiple peptides in the same vial?

This is generally not recommended for research purity purposes — mixing introduces variables that complicate data interpretation. Pre-blended vials (like KLOW 80mg) are formulated and tested for combined storage and are the preferred option when multiple compounds are needed together.

My reconstituted peptide looks cloudy — is it still good?

Most research peptides should yield a clear, colorless solution (GHK-Cu will be light blue). Cloudiness can indicate contamination, degradation, or incomplete dissolution. Swirl gently and wait a few minutes. If cloudiness persists, do not use — contact your supplier and check your COA batch records.

Research Use Disclaimer — All Evo Peptides products are for research use only and not for human consumption.

Research Compound

Bacteriostatic Water — 99%+ Purity · Janoshik COA Verified

Same-day shipping from Wisconsin · Free shipping on orders over $200 · For research use only.

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How to Reconstitute Peptides
with Bacteriostatic Water