If poor quality water is used without being treated first, or water quality is not maintained during use (such as with dump tanks), contaminants can be passed to livestock, poultry and food. Improperly treated water can also be a source of contamination.
This good agricultural practice applies to farms with poor water quality.
To protect the safety of food, livestock or poultry, treat water as required to maintain its quality or use an alternative source.
Choose the right method of water treatment. Make sure the type of water treatment chosen is the right one for the particular situation. Consult water quality professionals for more information on water treatment options.
A number of water treatment methods are available and can be used alone or in combination with several other treatment processes.
Filtration is the process of treating water contaminated with substances such as dirt or organic matter. For example, sand filters will remove large particles from the water. Granular activated carbon (GAC) filters, commonly known as charcoal filters, will filter particulate matter from the water and will also adsorb (soak up) dissolved organic matter and other contaminants. Membrane filtration is the most effective method for removing parasites such as Giardia and Cryptosporidium.
Ultraviolet (UV) light is a non-chemical method for killing micro-organisms such as bacteria, viruses (not retroviruses and rotaviruses), spores and cysts.
Coagulating water is the process of adding chemicals to water to make dissolved or suspended particles bind together and settle out. This process reduces the level of organic compounds, dissolved phosphorus, colour, iron and suspended particles.
Chlorination is the process of adding chlorine to water to kill bacteria and viruses but not parasites such as Giardia and Cryptosporidium. Two types of water chlorination – shock chlorination and continuous chlorination – are used in water treatment. Continuous chlorination (used for treating dump tank water) is a process of adding chlorine to water continuously to maintain a certain level of free chlorine in the water at all times.
Ozonation is the process of adding ozone to water to kill bacteria, viruses, parasites, mould and yeast spores. Ozone is a very efficient disinfectant and breaks down completely in water. However, due to its instability, it requires a high level of maintenance and operator skill.
Hydrogen Peroxide is a chemical added to water to kill bacteria, viruses and fungi. It is used along with ozone in what is called peroxone disinfection. As this disinfection process does not provide a measurable disinfectant residual it is not a recommended method for treating small water systems.
Biological water treatment is ideally suited to treat water that is highly coloured and has high dissolved organic carbon (DOC) and nutrient levels. It uses a natural ecosystem that removes colour and dissolved organic matter, but not micro-organisms. The treatment involves the use of naturally occurring micro organisms in the surface water to improve water quality.
Ask your chemical or water treatment supplier for approved water treatment aids, or refer to: Agriculture and Agri-Food Canada site for Agricultural Water Quality information.
Be prepared for the auditor to review:
There are few laws that impact on food safety regulating the treatment of water to be used in agricultural production. Generally, these requirements are laid out in laws regarding the processing of meat, fish and other food products, which are outside the scope of this document.