Water pH values for Livestock

This year the North Dakota Veterinary Diagnostic Laboratory (NDSU-VDL) has detected elevated pH values in livestock surface waters, especially in western North Dakota. Generally, the normal pH values of livestock water range from approximately 5.5 or 6.0 up to about 8.0 to 8.5. However, the lab has detected alkaline or basic pH values > 10 and up to 10.5 in water. At these elevated water pH values, animals could have irritation to the mouth and oropharynx, burning or irritation of the eyes, and refusal to drink. Extremes of water pH may dissolve materials from the ditches, pipes etc. and some could be toxic or impart an unpleasant taste to the water, particularly a metallic taste with a high water pH that cattle appear not to like. Little data is available on adverse effects of drinking highly alkaline or basic water in livestock. Often the high pH lakes or ponds contain a high concentration of minerals, particularly dissolved salts: sodium, calcium, magnesium carbonates and bicarbonates, sulfates, and other elements.  One alkaline lake in Tanzania, Lake Natron with a pH up to 10.5 due to sodium carbonate and sodium bicarbonate that leaches from the surrounding soil, supports an ecosystem of alkaline-adapted birds, fish, and algae but has killed many other animals.

Possible explanations for elevated water pH values include that in North Dakota over the last few years wet conditions could saturate alkaline soils and mobilize different constituents into wetlands. Apparently, North Dakota has some alkaline seeps that can contribute to the elevated water pH. High water pH is the outcome of many interacting chemical and biological processes. In some instances, altering a pond biology to a net daily carbon dioxide uptake to near zero can reduce high pH problems (e.g., reduce rapid plant growth or phytoplankton blooms of photosynthesis with carbon dioxide removal from water during the day, and increase pond respiration at night with carbon dioxide added to the water). Problems can occur with high pH of pond water where the total alkalinity or buffering capacity of water, defined as the ability to neutralize acids and bases (amount of carbonate, bicarbonate, and hydroxides in water), far exceeds water hardness (the amount of calcium and magnesium in water). While several management practices have been tried to reduce high pH water, some have significant drawbacks and often only achieve temporary benefits.

Note that human drinking water pH standards of 6.5 to 8.5 were established decades ago for aesthetic purposes and to protect plumbing from corrosion, rather than upon health-based criteria. In fact, it is not uncommon for some of the water treatment plants to release water with a pH range of 8.5 to 9.0 to help control pipe corrosions and minimize the potential to dissolve metals because the pH of water controls the solubility and concentrations of elements in water. As a point of interest, the laxative and heartburn remedy, Milk of Magnesia has a pH of 10.5 and a maximum dose of 4 tablespoons in an adult.

The NDSU-VDL offers regular and expanded water screens to help determine potability for livestock.  Please visit our water screen and expanded water screen test pages and our water collection guide for information on available tests and proper sample collection.

Michelle Mostrom, DVM, PhD, DABVT, DABT