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Montana State University Communications Services

When is Water Good Enough for Livestock?

By Jim Bauder
MSU Extension Soil and Water Quality Specialist

06/11/98 BOZEMAN -- With a variety of water qualities in Montana, many people have questions about whether water is good enough for livestock. In a dry year, as this one has started out to be, water problems are concentrated as water volume is reduced.

In Montana, the most common water problems relate to higher levels of total dissolved solids, alkalinity and nitrates. Generally, water's mineral content is reported as parts per million or milligrams per liter. The basic rule is that livestock should not drink water with total dissolved solids over 10,000 mg/l or a combination of nitrate and nitrite that exceeds 100 mg/l.

The USDA in various technical notes cites the following water content standards:

Content Recommendations for Water Suitable for Livestock

Aluminum (Al)

5 ppm

Arsenic (As)

0.2 ppm

Iron (B)

5 ppm

Cadmium (Cd)

0.05 ppm

Chromium (Cr)

1 ppm

Cobalt (Co)

1 ppm

Copper (Cu)

0.5 ppm

Fluoride (F)

2 ppm

Lead (Pb)

0.05 ppm

Mercury (Hg)

0.01 ppm


100 ppm


10 ppm

Selenium (Se)

0.05 to 0.10 ppm

Vanadium (V)

0.1 ppm

Zinc (Zn)

24 ppm

Total Dissolved Solids

10,000 ppm

Magnesium + Sodium sulfates

5,000 ppm

Alkalinity (carbonate + bicarbonate)

2,000 ppm

The saltiness of water is commonly measured by total dissolved solids, which is approximated with the specific or electrical conductance, as measured in either umhos/cm or deceseimens/meter. The following table describes various degrees of water saltiness and their suitability for watering livestock.

Suitability of Saline Water for Livestock

less than 1,500 umhos/cm or total dissolved solids of less than 1,000 mg/l relatively low level of salinity excellent for all classes of livestock
1,500-5,000 umhos/cm or
TDS of 1,000 - 3,000 mg/l
satisfactory for all classes of livestock; may cause temporary, mild diarrhea in livestock not accustomed to the water
5,000-8,000 umhos/cm or TDS of 3,000-5,000 mg/l satisfactory but may cause temporary diarrhea or be refused at first; poor quality for poultry
8,000-11,000 umhos/cm or TDS of 5,000-7,000 mg/l can be used with reasonable safety for dairy and beef cattle, sheep, swine, and horses; avoid using with lactating animals
11,000-16,000 umhos/cm or TDS of 7,000-10,000 mg/l unfit for poultry and swine; considerable risk for lactating livestock; should be avoided although older ruminants, horses may subsist on water of this quality under some circumstances
over 16,000 umhos/cm
or TDS over 10,000 mg/l

Conductance is sometimes reported as mmhos/cm, which is umhos/cm divided by 1000. To convert to umhos/cm, multiply mmhos/cm by 1000.

Send questions or comments to Carol Flaherty, MSU Communications Services, Bozeman, MT 59717 or to Bauder and Flaherty with this link:

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