Clearing up the water

Written by Dr. Jim White on .

Cows consume more pounds of water a day than anything else. If water quality or water quantity are issues, your cattle have a problem.

The most common water quality concerns in the Midwest are high iron and high anion contents. Water above certain thresholds in these minerals can affect cow performance. Iron over 0.3 ppm or anions (sulfate + chloride levels greater than 1,000 ppm) are troublesome.

Water treatment methods available to remove the iron, sulfate and chloride include chlorination with filtration; ion exchange; ozonation; reverse osmosis; and an oxidizing filter. None of them are cheap.

Working with too much iron

The recommended maximum tolerable concentration of iron in drinking water is 0.3 ppm. Concentrations more than this can be detrimental to normal health and lactation performance. The common chemical form of iron in feed ingredients is ferric iron (Fe+3) which is insoluble (although low pH iron, say in calcium phosphates will be soluble). The iron in drinking water (Fe+2) is highly soluble and absorbable. Excess absorbed iron ingested from drinking water can lead to cellular stress and inhibit copper and zinc absorption.

High iron in drinking water also may reduce water intake, apparently because ferrous iron is unpalatable. When cows don’t drink enough, feed intake and milk production can suffer.

Aside from animal intake, the residue formed by iron-loving bacteria in water troughs can affect flow rates and water volume through pipes. Treating high-iron drinking water with 20 ppm hydrogen peroxide eliminates these microbes. However, immediately after treatment with hydrogen peroxide, there is a good chance there will be iron debris in the line. Check waterers to make sure everything is still flowing.

Effects of sulfate and chlorine

Excess sulfate and chloride can negatively influence a cow’s digestion, electrolyte balance, acid-base status and lactation. If the sum of the concentrations of sulfate plus chloride is greater than 1,000 ppm an evaluation should be done to determine if the anions are affecting cow health and performance.

High concentrations of sulfate plus chloride, (greater than 1,000 ppm) in water can reduce water consumption. In research at Michigan State University, animal scientists found the maximum tolerable concentrations of sulfate range from 3,500 ppm to 1,450 ppm sulfate. In that study, heifers discriminated against the water containing 1,450 ppm sulfate and rejected water with 2,800 ppm sulfate. Other research has shown levels of 3,200 to 4,700 ppm sulfate makes water unpalatable to livestock. Meanwhile, high-sulfate (1,200 ppm) in drinking water reduced performance of transition fresh dairy cows by causing reduced feed intake and milk yield, and increased incidences of retained fetal membranes and abomasal displacement.

Dealing with hydrogen sulfide

In water, sulfur present as hydrogen sulfide tends to smell like rotten eggs. While the research at Michigan State showed water intake increased when water without the smell was offered, scientists there didn’t find what concentration of hydrogen sulfide or what intensity of smell reduces normal water intake of cattle. It could be that animals simply adapt to the smell and maintain typical levels of intake if no other water is available.

Water-treatment options

If lab results show you have concentrations of iron, sulfate or chloride high enough to affect cattle performance, finding a different water source may be the best solution. If that’s not an option, treating water can work. Whether water treatment is cost effective will depend on your situation.

There are a several ways to treat water, each has its limitations, complications and expense.

Chlorination can remove dissolved iron, manganese, and hydrogen sulfide if followed by mechanical or activated carbon filtration. If not properly operated, a chlorination system can be expensive and potentially hazardous if chlorine byproducts escape. Cows dislike getting a strong waft of chlorine in the nose. Even adding slow release chlorine tablets into water tanks can affect water intake.

Use of mechanical filters is recommended with chlorination to remove soluble and insoluble particles and to reduce plugging or wear on equipment. Activated carbon filters use carbon granules to absorb free chlorine as well as other things that can contribute to odor, off-tasting water and contaminants like mercury, pesticides and radon gas.

A cation-anion exchange system can be used to remove iron and manganese at relatively low concentrations (less than 1 ppm).

Ozonation can remove soluble iron and manganese if water passes through mechanical or activated carbon filtration. Ozonation also destroys microorganisms. This method can be used to remove color, offtaste, odors and hydrogen sulfide.

Reverse osmosis technology removes iron, sulfate, chloride and other unwanted compounds. Impurities are filtered from water using membranes. However, initial and maintenance costs are steep, and the process requires a lot of volume because the rate of filtration is slow. Meanwhile, you’ll be collecting the filtrate—the stuff on the filter to dispose of. If you pull water out of the ground and treat it, what’s diverted from consumption is technically waste water. What happens to the waste water might be regulated by county, state or federal agencies. Be sure to check first.

Finally, oxidizing filters remove iron and manganese through filtering and chemical reactions. Hydrogen sulfide can also be removed in this manner.


  • Subscriptions
  • Advertising
  • This email address is being protected from spambots. You need JavaScript enabled to view it.


  • This email address is being protected from spambots. You need JavaScript enabled to view it.
  • FAQ
  • Copyright Notice