Chlorine, chloramine, peroxide-based treatments, and other oxidizing sanitizers play an important role in routine water-system management. During administration of a live vaccine, however, those same oxidizing compounds can damage the organisms that must remain viable until pigs consume the vaccine.

In an independent laboratory study performed by Whitbeck Laboratories, a live Salmonella choleraesuis vaccine marketed for swine was evaluated in sterile deionized water, water containing 4 ppm free chlorine, and the same chlorinated water treated with an ASP-provided stabilizer. Unstabilized 4 ppm chlorinated water produced no recoverable vaccine organisms at 0, 2, 4, or 6 hours. In contrast, the ASP-stabilized chlorinated water supported recoverable vaccine counts similar to those in the nonchlorinated water control throughout the six-hour evaluation (Whitbeck, 2012).

The study concluded that stabilization was necessary to protect viability of the live vaccine in the presence of chlorine. Correct reconstitution and accurate medicator settings do not guarantee delivery of the intended viable vaccine—or a stable, water-administered active ingredient—if oxidizing water conditions remain uncontrolled.

Correct reconstitution and accurate medicator settings do not guarantee delivery of the intended viable vaccine if oxidizing water conditions remain uncontrolled.

Vac-Pac and Vac-Pac Plus are designed for use in drinking water when administering water-delivered treatments. Their formulation addresses three water conditions that can compromise live biologicals and sensitive water-administered compounds (ASP, 2026; Kamau et al., 2010):

• Oxidizers: Vac-Pac products reduce the harmful effects of chlorine and other oxidizing agents that can damage live organisms and sensitive compounds.

• pH: The formulations buffer prepared water toward a more suitable range for these treatments.

• Electrolyte balance: The stabilizers support appropriate tonicity in prepared treatment water with electrolytes rather than fermentable sugars

Vac-Pac Plus adds another operational advantage: an intense blue visual marker. Uniform blue color confirms that the stabilizer has mixed into the water. As the colored water moves through the lines, it gives the crew a visible means to confirm system priming, monitor movement to remote drinkers, and verify flushing after administration.

Vac-Pac Plus dissolves immediately when mixed as directed, either directly in a tank mix or as a stock solution. Each 4-ounce pack stabilizes 256 gallons of water, allowing personnel to add the vaccine without waiting for an effervescent reaction to finish or a tablet to dissolve. The Farm-Pac presentation is an ideal solution for smaller groups of pigs because of its resealable jar. Dosed at 100 grams per 1,000 liters (264 gallons), each 20-gram capful stabilizes approximately 50 gallons of water (ASP, 2018).

Water stabilization is relevant wherever sensitive active ingredients depend on drinking water for delivery. That includes label-approved oral programs involving Lawsonia intracellularis, Salmonella, selected E. coli and erysipelas products, as well as other live biologicals, probiotics, and label-appropriate pharmaceutical applications.

Each product has its own label, approved administration route, pig-age recommendation, antimicrobial restrictions, and mixing instructions. A water stabilizer does not replace those requirements. It protects the delivery environment so the product has a better opportunity to reach the pig in the form intended by its manufacturer.

The same principle can also apply to pharmaceutical products administered through drinking water. For example, Safe-Guard® AquaSol® is a fenbendazole oral suspension labeled for administration to swine through drinking water, subject to its own dosing and withdrawal requirements. ASP reports that chlorine reduced fenbendazole activity immediately in test water, while Vac-Pac- or Vac-Pac Plus-stabilized water prevented the reported loss of fenbendazole at mixing and after 24 hours (ASP, 2019; Merck Animal Health, 2026).

For producers, this reinforces an important distinction: water quality can affect not only live vaccine viability but also the stability of certain water-administered active ingredients.