Water Quality in Swine Barns: How do we define it?

The importance of water in swine production cannot be overstated, as it is essential for normal metabolic function and is the nutrient consumed in the largest quantity by pigs. Water also is critical for regulating body temperature, excreting waste, and is required to maximize feed consumption. Therefore, insuring
pigs have access to water adequate in both quality and quantity is paramount.

Water Quality
When analyzing water quality in a swine facility, the producer should primarily consider bacterial contamination in the water source as well as the mineral composition and overall concentration of dissolved solids. Pigs generally are resilient to variation in water quality, but certain elements and substances should be monitored to understand the potential risk.

Water and water systems for swine facilities may contain a variety of bacteria, protozoa and some viruses¹. It is important to test and monitor for contamination and any potential threats to animal health and well-being, but also to prevent the accumulation of biofilms. Biofilms are the result of a collection of bacteria or fungi that coexist together in water lines. The challenge with biofilms is that as different bacteria colonize to a multicellular form, they create a matrix that encases them and can make them resistant to many of the common antibiotics producers may use in production. This can become a challenge as buildup can restrict and reduce waterflow and drinker function. Water lines should be cleaned routinely to control the presence of microbes in the water. Charging the water lines with a 1-3% hydrogen peroxide solution for 24 to 48 hours can effectively break down and flush out any buildup in the pipes. This procedure should be done when the barn is between groups and no pigs are present. After charging the lines, it is important to remove all water nipples and flush the lines. This also is a good time to clean and sanitize water nipples and drinkers and allow these to thoroughly dry, as another step to reduce pathogen loads. Chlorinating water lines is another effective way to manage coliform count while pigs are in the barn. Environmental Protection Agency (EPA) guidelines for maximal residual free chlorine levels to control bacteria are 4 mg/L for chlorine or chloramine disinfection, and 0.8 mg/L when using chlorine dioxide. Target level of free chlorine in treated water is 3-5 ppm. Chlorine levels that exceed this range could result in reduced water intake. Conversely, levels below the target range may not effectively disinfect the lines. Citric acid also may be a suitable option to acidify the water lines to help suppress pathogen growth. When using citric acid, it is important to test the pH of the water at the nipple with a target pH of 4.

Water hardness describes the level of calcium and magnesium in the water. Elevated calcium and magnesium will not impact health and performance of the pigs directly,² but over time can accumulate in water lines, potentially limiting the flow rate of water to the pigs. If analysis determines water in a swine barn exceeds 120 ppm of hardness, it is considered hard water. Being aware of the hardness level of water on your farm can help you maintain facilities and keep equipment working optimally. Water hardness can be addressed by installing a water softening system.

The presence of iron in water sources is common across many regions. It manifests itself as iron oxide (rust) after being pumped from the ground and exposed to oxygen at the surface. Rust can be problematic in swine barns over time as it builds up and can plug nipple drinkers and obstruct other parts of the water delivery system. Iron or rust sediments can be managed easily, and water disruptions prevented, by installing in-line filtration. Iron is a critical trace mineral in swine diets, although it can have negative effects. Some evidence has shown excessive iron supplementation can negatively impact gastrointestinal health by reducing villus height and altering the morphology in the small intestine. Iron in water also can support growth of pathogenic bacteria, and the production of biofilms that limit the function of the water system. While the assumption is that most of the iron in surface water is in the form of iron oxide and therefore low bioavailability to the pig, being aware of the iron level in swine barn water sources is important to know the total dietary iron pigs may be consuming.

Elevated levels of sulfate salts can be cause for concern. Sulfates above 500 ppm can have a laxative effect on growing pigs, which is observed more frequently the younger the pig. As such, the maximum recommended level for sulfates is 1,000 ppm5. Even so, research has shown pigs having diarrhea can withstand rather high concentrations of sulfates (1800 mg/L; 1650 mg/L6,7) and not have average daily gain or feed conversion impacted. Reverse osmosis systems are effective at removing sulfates from drinking water and reducing loose stools; however, such systems are costly to install and have not been shown to positively impact pig growth performance. When examining sulfates and the effects on stool characteristics, it is important to be mindful of other dietary sources, such as DDGS, that add to total sulfur levels consumed and can contribute to gastrointestinal disturbances. Further research is needed to assess the impact of a chronic diarrhetic state as it relates to the pig’s susceptibility to other

Total Dissolved Solids
Total dissolved solids (TDS), a measure of total minerals in the water, can vary considerably between production sites. In general, total dissolved solids will not impact pig health or performance, but may cause temporary diarrhea and increased water intake in water sources exceeding 6,000 ppm10. Gilt and sow reproduction was not shown to be affected when the animals were offered water containing 5,060 ppm TDS from day 30 of gestation to day 28 of lactation11. Even so, new research is needed to assess potential effects on TDS on modern swine genetics and reproductive impacts. Being aware of the mineral composition can help assure dietary mineral composition is adequate for the pig. In general, water with TDS levels below 1,000 ppm is no risk to swine, and water with TDS levels exceeding 7,000 ppm may present some risk to gestating or lactating sows and for growing pigs under stress.

The pH level of water rarely is a health or performance concern, because most water samples test in the acceptable range of 6.5-8.513. Knowing a barn’s water pH level is important when using certain medications that are pH sensitive. If the pH is not correct for a certain medication, that medication could precipitate out in the water, which would reduce its efficacy and build residues in the delivery system. Acid or base can be added to the drinking water when medications are being provided to the pigs in this
manner. Contact your supplier for instructions specific to their product.

Nitrate and Nitrite
It is important to monitor nitrate and nitrite levels in pig water supplies. Nitrite can reduce the blood’s oxygen-carrying capacity, resulting in hypoxia. It is thought to be of greatest concern in the younger pig, although it is generally not an issue with those young pigs still getting nutrients from the lactating sow. Previous work has shown the conversion of nitrate to nitrite is necessary for toxicity and mortality to occur in growing pigs, though the nitrate level would have to exceed 300 ppm to form enough nitrite to cause toxicity. The current standard for nitrates is 100 ppm and for nitrites is 10 ppm.

Testing Water
Annual samples are recommended to detect any changes in water quality and suitability for pigs. Samples should be collected in a clean container at both a point closest to where the water supply enters the barn and at the end of the water line. This allows evaluation of contents in the water supply and in the delivery system to the pigs.

Matt Romoser, swine specialist Iowa State University Extension
and Outreach; Laura Greiner, assistant professor, and John
Patience, professor emeritus Department of Animal Science,
Iowa State University


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