Editor's note: The following is from a paper presented by G.E. Doughan, DVM, and colleagues at Iowa State University College of Veterinary Medicine during the 2024 Annual Meeting of the American Association of Swine Veterinarians.

Water source and water line biofilms may pose a biosecurity risk for the introduction of pathogens to the farm. Maximizing water biosecurity and medication efficacy can increase pig livability for all swine.

Water can serve as a vector and reservoir for pathogens. Many studies have documented the presence of human and livestock pathogens in surface water and groundwater sources. Pathogens capable of transmission through water of relevance to swine include Salmonella, E. coli, Actinobacillus pleuropneumoniae, Leptospira, influenza A, rotavirus and others.

Water is one of the largest inputs into swine farms with up to thousands of gallons consumed daily, which presents a biosecurity risk. Biofilms in water distribution systems (WDS) in swine farms may serve as a reservoir for pathogens and could reduce the efficacy of overall biosecurity procedures.

Water biosecurity

Water biosecurity needs to be assessed in two areas: 

1. the biosecurity of the water source 
2. the biosecurity of the water once it is inside the farm

Swine WDS are open, low-pressure systems with terminal line “dead-ends” that provide an environment that is optimal for biofilm development. Water quality parameters often include hard water that has elevated mineral contents which biofilms can use as a resource.

Water-administered treatments such as electrolytes, probiotics and live attenuated oral vaccines allow for additional nutrient sources which are potential bacterial introduction points into these systems.

Organisms can be introduced into the system through the water medicator (and poorly cleaned stock buckets) and from the pigs themselves as they use drinking water apparatuses.

Coliform analysis

A study was done in which water samples were collected from six wean-to-finish sites in central Iowa. The samples were collected at 10 time points over a 77-day period at each barns’ private well access point and two rooms from a flush valve from each site.

Preliminary results from four of sites showed a similar pattern: the well had relatively low concentrations of coliforms, but the total coliforms in rooms at each site were substantially above those of the well sample for most of the sampling sites.

This pattern indicates that water quality decayed since entering the farm from either biofilm shedding organisms into the water lines or from organisms being introduced on the farm, or both.

Water line disinfection

Water line disinfection treatments may be applied to reduce and eliminate the biological load in water coming into the farms, especially between groups of pigs.

Best practices have been difficult to develop for water biosecurity programs as they will vary by the farm’s WDS, water sources, water quality and other factors. Water biosecurity programs must focus on treating the incoming water, targeting mineral and biofilm buildup inside water lines.

Preliminary testing shows that a one-time disinfection event in wean-to-finish farms reduces or eliminates the biofilm load initially, but biofilms actively develop 72 hours later. This warrants the use of a disinfectant on a continual basis.

Water medications

Best practices for administering water medications should begin at the point of entry: the water medicator. These practices include:

• using a clean stock bucket with each medication administration
• changing the stock solution every 12 to 24 hours
• frequent mixing with an agitator to keep medications in solution
• ensuring the water medications are properly mixed to achieve the correct dose

Studies have shown that improper dosing in water medications and a lack of maintenance of medicators is found frequently on swine farms. Improper dosing can lead to increased medication costs, potential toxicity, decreased antimicrobial efficacy and further antimicrobial resistance.

Water quality parameters such as pH, water hardness, trace mineral components, and presence of chlorine or disinfectants can decrease medication solubility, stability, and efficacy of water medications. The presence of chlorine, peroxides or acids can decrease oral vaccine efficacy.

Once the medicated water reaches the main WDS in farms, biofilms could further impact medication effectiveness. Biofilms that are exposed to antimicrobials over time may experience reduced growth and become stationary; in this phase, bacteria are more tolerant to antibacterials.

Ensuring proper medication dosages and eliminating biofilms from the WDS in swine farms is essential to maintain effective antimicrobial treatments in the future.