When should water sanitizers be flushed out of drinking lines before administering live vaccines via drinking water?

Administering live viral vaccines (such as Newcastle Disease or Infectious Bronchitis) via drinking water is common on layer farms, but sanitizer residues can easily ruin the process. Active sanitizers like chlorine, chlorine dioxide, and hydrogen peroxide are designed to kill microorganisms, and even trace amounts (above 0.1 ppm) will neutralize the live vaccine virus. To ensure full vaccine efficacy, water treatment systems must be turned off and the lines thoroughly flushed with fresh, untreated water at least 24 to 48 hours before vaccination. Vaccine stabilizers (such as skim milk powder or sodium thiosulfate) should also be added to the vaccine water to neutralize any remaining chlorine ions in the pipes. Vaccine protocols are in the Poultry Encyclopedia, water line neutralizers and testing strips are sold on Poultry Plaza, daily bird rates are on Poultry Rates, and vaccinated layer flocks are traded on Murghi Mandi.