Causes of Rust in Horse Waterers

Horse watering troughs in fields are constantly exposed to the elements, and are susceptible to rust. Most all-metal troughs are now made from galvanized steel, which is more rust-resistant than plain steel. Many horse owners are now choosing robust plastic and rubber troughs over metal as they are less at risk of rust. However, these plastic troughs can become brittle in cold weather and fracture.

  1. How Rust Forms

    • Rust is a chemical process formed by the reaction of oxygen dissolved in water with iron. The reaction causes iron and steel to corrode, weaken and eventually disintegrate. Others metals become corroded, but they do not rust. Iron or steel left in a dry environment will rust only very slowly, if at all. However, metal that is constantly exposed to the elements, such as in field water troughs, is particularly at risk.

    Rust and Galvanized Steel

    • Galvanized steel was invented for use in situations like field water troughs where the steel is constantly exposed to the atmosphere. Galvanization involves dipping the steel in melted zinc to produce a thin layer, which reacts with the air to produce zinc oxide. This layer protects the steel from coming into contact with water. However, it is also the first element to be attacked in the rusting process, so oxidation will gradually eat away at the zinc and leave the underlying metal exposed.

    White Rust

    • Sometimes, galvanized steel troughs will appear to have a white bloom. This is known as white rust, and is a reaction between unoxidized zinc and impurities in the water. This white rust will eventually eat away at the zinc and leave the steel below exposed to oxidization and corrosion. Sometimes, a white powder seems to take over galvanized steel and galvanized steel wool.

    Other Causes of Rust

    • In addition to the standard oxidation process, rust can be accelerated by salt water. If you live near the coast, it may be better to consider plastic troughs.

      Horse troughs are particularly vulnerable to damage from horses kicking or rubbing against the metal. This will remove the protective layer of zinc, and accelerate the corrosion process of the steel underneath.

      Horses will not drink from a dirty trough, so once particles of rust start to appear in the water the trough should be cleaned out or replaced.