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Cleaning your horse's water tank

Quick facts

  • Clean your water tank often throughout the year to prevent algae growth and unclean conditions.

  • Always use bleach in the recommended amounts and follow the respective wait time.

  • Don’t use scented bleach products.

Horse drinking
Keeping your horse’s water and tank clean encourages drinking and helps keep your horse healthy.

Water is one of the seven key nutrients required by horses. Horses should always have access to good quality water. Frequent water tank cleaning is important, especially in warm months and with plastic tanks.

How to clean your water tank

  1. Empty the tank.

  2. Scrub it clean.

  3. Rinse the tank with a 10 percent bleach solution (1 part bleach to 9 parts water).

  4. Rinse it twice more with clean water.

  5. Refill the tank. The horses can safely drink from it right away.

Adding bleach to your water tank

You can add small amounts of bleach to existing water in a tank at a level that is safe for your horse to drink.

  • Effectively disinfect water in tanks by using unscented household bleach in recommended quantities.
  • After adding bleach, wait at least one hour before letting your horses drink from it. This will allow the chlorine time to dissipate.
  • If the water is less than 50 degrees F, increase the waiting period to two hours.

If you want to treat water from a lake, stream or shallow well, double the amount of bleach you use and wait two hours before letting your horse drink. These water sources can contain chlorine resistant parasites from animal droppings.

Always use the recommended bleach levels and wait the recommended amount of time to prevent over application, which can lead to toxicity. The table below outlines how much bleach to add to specific amounts of water to disinfect relatively clean water. Only use unscented bleach products.

Gallons of water to disinfect Amount of bleach needed*
1 2 drops
5 11 drops
50 1 3/4 teaspoons
100 3 1/2 teaspoons
500 6 tablespoons

*Will produce water with about 2 parts per million of chlorine. 

How often should you clean your water tank?

You should clean your water tank often, even in the winter, to avoid algae growth and unclean conditions. Algae growth may cause your horse to drink less and can be toxic in some cases.

What affects water quality in your tank?

Many factors contribute to a dirty stock tank and poor water quality. Dirt, manure, feed droppings and algae can all contaminate tank water.

In small amounts, algae can turn the water green and produce a bad odor, which may reduce how much water your horse drinks. In larger amounts, algae can make your horse sick.

Water temperature can greatly affect horse water intake. Generally, horses prefer cool to lukewarm water over hot or very cold water. 


Author: Devan Catalano and Marcia Hathaway, College of Food, Agricultural and Natural Resource Sciences; Bradley Heins, Extension dairy specialist; Krishona Martinson, Extension equine specialist; and Shahram Missaghi

Reviewed in 2023

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