The risks to bird health from microbial contamination are higher than risks from chemical contamination. This is because the health risks caused by chemicals are chronic rather than acute and tend to be longer-term unless a specific contamination event has occurred.
On the other hand, the health risks caused by microorganisms are generally acute, short-term, and can severely affect bird performance. Therefore, you should typically give microbial water quality criteria a higher priority than chemical water quality criteria when assessing water quality in meat chicken farms.
The best practice water quality criteria presented in Table 1 (below) were determined from the concentrations listed as levels considered average in Ross (2018), Cobb (2018), and Watkins (2008). When the concentration limits varied between these three sources, the most conservative value was selected.
Many chemical and microbial contaminants can affect water quality and bird health. These water quality criteria represent major contaminants and are used as water quality indicators of other contaminants of a similar type. It is important to refer animal health problems to your veterinarian.
Notes
The unit milligrams per litre (mg/L) is equivalent to parts per million (ppm).
To convert measurements of electrical conductivity (EC) to total dissolved solids (TDS), or vice versa, use the equations below:
TDS (mg/L) = Electric Conductivity (EC) (dS/m) * 640 (where EC from 0.1 to 5dS/m)
TDS (mg/L) = EC (dS/m) * 800 (where EC >5dS/m)
An online conductivity converter is available from www.lenntech.com/calculators/conductivity/tds_engels.htm
Concentrations of nitrate can be expressed in either of two ways:
- “nitrate as nitrogen” (symbol: NO3-N) or
- simply as nitrate (NO3).
To convert NO3-N to NO3 in mg/L, multiply NO3-N by 4.42.
Table 1. Recommended water quality criteria for poultry
| Criteria | Unit | Best practice level | Acceptable range | Notes |
|---|---|---|---|---|
| Microbial | ||||
| Faecal coliforms e.g. Escherichia coli | CFU/ml | Below detection | Below detection | Health-based target. Levels above detection limit indicate faecal contamination. |
| Physical quality | ||||
| Electrical conductivity (EC) | dS/m | 0–1.56 | 0–4.69 | Measures the ability of water to conduct an electric current. It depends on the concentration of charged ions (e.g. salts). |
| Total dissolved solids (TDS) | mg/L | 0–1000 | 0–3000 | Calculated from EC or vice versa. |
| Colour (true) a | HU | 0–15 | >15 | Approximate estimation of dissolved organic matter. Changes can indicate issues with source or treatment processes. |
| Hardness | mg/L | 0–100 | 0–200 | There are no health effects directly attributable to hardness. However, high concentrations will cause scale and can interfere with the effectiveness of disinfectants and medications. It can corrode cool cell pads. |
| pH | pH | 6.5–7.8 | 6.5–8.0 | Low pH can corrode water systems and cause metal leaching. High pH can reduce the effectiveness of disinfectants and encourage scale to form. |
| Metals | ||||
| Calcium | mg/L | 60 | 0–600 | There are no health effects directly attributable to calcium. However, values above 100mg/L may cause scaling. |
| Copper | mg/L | 0–0.002 | 0–0.6 | High levels can cause oral lesions, gizzard erosion, and liver damage. High levels of copper are usually caused by acidic water conditions causing metal leaching. |
| Iron | mg/L | 0–0.2 | 0–0.3 | Can cause bacteria to grow and can also cause scaling. |
| Lead | mg/L | 0 | 0–0.01 | Toxic heavy metal that can cause weak bones and fertility problems in meat chickens. |
| Magnesium | mg/L | 0–14 | 0–125 | High concentrations will cause scale and can have a laxative effect, particularly if high concentrations of sulphate are also present. |
| Manganese | mg/L | 0–0.01 | 0–0.05 | Can cause bacteria to grow and cause scaling. |
| Potassium | mg/L | 0–300 | 0–500 | High concentrations of potassium have no known adverse health effects. However, its counterions (e.g. chloride) have laxative effects. |
| Sodium | mg/L | 0–32 | 0–150 | High concentrations can have a laxative effect and promote Enterococcus bacteria to grow. |
| Zinc | mg/L | 0–1.5 | 0–1.5 | Higher concentrations may reduce bird growth rates. |
| Non-metals | ||||
| Chloride | mg/L | 0–14 | 0–150 | Combined with high sodium levels, it can have a laxative effect and promote Enterococcus bacteria to grow. |
| Fluoride | mg/L | 0–1.1 | 0–2 | High concentrations can cause soft bones (fluorosis). |
| Compounds | ||||
| Nitrate (as nitrogen) | mg/L | 0–10 | 0–25 | High concentrations can cause poor growth and feed conversions and can indicate organic material faecal contamination. |
| Sulphates | mg/L | 0–40 | 0–250 | High concentrations can have a laxative effect. |
| a These values are from the Australian drinking water guidelines (2011). | ||||
If there is a specific water quality issue, you can also test the additional water quality criteria in Table 2. These analyses are not regularly needed unless a water quality issue has been previously identified. These analyses can provide extra information to help you identify and implement a targeted control measure.
Table 2. Additional criteria that can be analysed in response to identified water quality issues
| Water quality issue | Criteria | Unit | Best practice range | Acceptable range | Notes |
|---|---|---|---|---|---|
| Microbial | |||||
| Positive Escherichia coli | Total bacteria | CFU/ml | 0–100 | 100–1000 | Estimate the concentration of microorganisms, including bacteria, yeast, and mould spores in a water sample. |
| Positive Escherichia coli | Bacterial coliforms | CFU/ml | 0–50 | 1–50 | Estimates bacteria that are found in the soil, in water that has been contaminated by surface water, and also in human or animal waste. |
| Birds have had major health issue from a waterborne microbe | Species of fungi, bacteria, virus, protozoa and toxin identified | – | – | – | Investigative—to help identify the issue. Common pathogens that are investigated include: Salmonella, Campylobacter, Giardia, Cryptosporidium and Orthomyxoviridae. |
| Cyanobacteria (blue-green algae) | |||||
| Source water has a major algal bloom | Chlorophyll a | μg/L | 0–7 | 0–15 | These values are from the New Hampshire Department of Environmental Services (2017) and should only be used as a guide. |
| Birds have had major health issue from cyanobacteria | Microcystins a | μg/L | 0–1.3 | 0–1.3 | Expensive test to quantify one type of toxin. |
| Species and toxin identification | variable | – | – | Expensive test to identify species so treatment can be targeted. | |
| Physical quality | |||||
| Higher than average solids in water | Turbidity a | Nephelometric turbidity unit (NTU) | 0–1.0 | 0–5 | Investigative—to help identify the issue. |
| If there are ongoing issues with organic matter in system | Total organic carbon (TOC) | mg/L | – | – | Investigative—to help identify the issue. |
| Dissolved organic carbon (DOC) | mg/L | – | – | ||
| Silica scale and reverse osmosis (RO) membrane scale | Silica | mg/L | < 80 | < 80 | Can contribute to scale and can also affect RO. |
| Metals | |||||
| Possible heavy metal contamination | Antimony a | mg/L | 0–0.003 | 0–0.003 | These values are from the Australian drinking water guidelines (ADWG) and should only be used as a guide. |
| Arsenic a | mg/L | 0–0.01 | 0–0.01 | ||
| Cadmium a | mg/L | 0–0.002 | 0–0.002 | ||
| Chromium as Cr(VI) a | mg/L | 0–0.05 | 0–0.05 | ||
| Mercury a | mg/L | 0–0.001 | 0–0.001 | ||
| Compound | |||||
| If cyanide contamination is suspected | Cyanide a | mg/L | 0–0.08 | 0–0.08 | Values are from the ADWG and should only be used as a guide. |
| If there is an ongoing issue with nitrate | Nitrite a | mg/L | 0–3 | 0–3 | Rapidly oxidises to nitrate. Values are from the ADWG and should only be used as a guide. |
| Pesticides | |||||
| If pesticide contamination is suspected | Individual pesticides | μg/L | 0–0.1 | 0–0.1 | These should only be used for guidance, as they are general values from the European Drinking Water Directive (DWI, 2010). Specific pesticides can have highly variable guideline health values. For further information on guideline health values for specific pesticides, please refer to the ADWG. |
| Total pesticides | μg/L | 0–0.5 | 0–0.5 | ||
Table 3 is a summary of water quality criteria definitions and common treatment options you can use to control them.
Table 3. Definitions of water quality criteria
| Characteristic | Definition | Common treatment options and comments |
|---|---|---|
| Total bacteria | Total viable count (TVC) is a non-specific test that estimates the concentration of microorganisms, including bacteria, yeast and mould spores in a water sample. The TVC represents the number of colony-forming units (CFU) per millilitre (mL) of the sample. While most are not disease-causing organisms, they are an indicator of the sanitary condition of a water supply. | Pre-treatment Disinfect water – continuous system Shock disinfection Clean the system between flocks |
| Bacterial coliforms | Total coliforms can include bacteria from: soil, surface water, and human or animal waste. While most are not disease-causing organisms, they are an indicator of the sanitary condition of a water supply. |
|
| Faecal coliforms e.g. Escherichia coli (E. coli) | E. coli is a group of bacteria whose presence indicates a high probability of recent faecal contamination of drinking water. | |
| Chlorophyll a | Chlorophyll is a specific form of chlorophyll used in oxygenic photosynthesis, and it indicates the presence of blue-green algae (cyanobacteria). | Pre-treatment filter Reverse osmosis Coagulation |
| Microcystins | Hepatotoxic peptide produced by a range of cyanobacteria expressed as ‘Microcystin–LR’ toxicity equivalents. | |
| Total dissolved solids (TDS) | TDS consist of inorganic salts and small amounts of organic matter that are dissolved in water, including: sodium, potassium, calcium, magnesium, chloride, sulphate, bicarbonate, carbonate, silica, organic matter, fluoride, iron, manganese, nitrate, nitrite and phosphates. Although TDS is not generally considered a primary contaminant (i.e. there are no health effects directly attributable to TDS), it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a range of chemical contaminants. High TDS can reduce the palatability of drinking water. | Reverse osmosis Nano-filtration (to a lesser extent) |
| Turbidity | Turbidity is caused by the presence of fine suspended matter such as clay, silt, small inorganic and organic matter, plankton, dissolved coloured organic compounds and other organisms in the water. | Filtration Coagulation |
| Colour (true) | Colour is caused by dissolved organic matter, which originates from soils and decaying vegetation in catchment areas. True colour is measured after filtering the water to remove the particulate matter. | Filtration Activated carbon Coagulation |
| Hardness | Hardness is associated with bicarbonate, sulphates, and calcium carbonate. These substances release hydroxyl ions when dissolved in water and are principally bicarbonate ions and carbonate ions. These compounds act as buffers in water; that is, they buffer the water against sudden changes in pH. Hardness causes scale, which reduces pipe volume and makes drinkers hard to trigger or leak and it can corrode cool cell pads. High concentrations can also give water a bitter taste that birds don’t like. Hardness can also reduce the effectiveness of soaps, disinfectants and the administration of some medications. | Reverse osmosis Nano-filtration (to a lesser extent) Ion exchange Aeration can remove carbon dioxide Acidification can be used to dissolve scale caused by hardness Do not use ion-exchange if the water is already high in sodium unless using potassium chloride instead of sodium chloride. |
| pH | The pH is a measure of the acidic or alkaline nature of the water. pH is controlled to minimise corrosion and encrustation in pipes and fittings. | Increase pH with soda ash (Na2CO3), lime Ca(OH)2 or sodium hydroxide (NaOH). Decrease pH with phosphoric acid, sulphuric acid and hydrochloric acid for strong alkalinity, citric acid and vinegar for weak alkalinity. |
| Calcium | Calcium is a dietary requirement for meat chickens. Calcium occurs in water naturally from the weathering of rocks in the source waters catchment area, and it is a major contributor to water hardness. Calcium itself does not negatively affect poultry health. However, it can cause scale build-up and negatively affect water lines and fogging systems. | Refer to ‘hardness’ for treatment methods. |
| Copper | Copper is a dietary requirement for meat chickens. It is widely distributed in rocks and soils as carbonate and sulphide minerals and occurs in water via dissolution from natural sources or plumbing containing copper. Low pH water will cause copper pipes to leach. | Reverse osmosis Ion exchange |
| Iron | Iron is a dietary requirement for meat chickens. It occurs naturally in water, usually at <1mg/L, but up to 100mg/L in groundwater. Iron-oxidising bacteria can cause blockages and corrosion issues in water with high iron concentrations. Iron concentrations as high as 600mg/L have been shown not to affect bird health but will have detrimental effects on water lines and fogging systems (Fairchild, B. D. et al., 2006). High concentrations can give the water a bitter taste that may decrease consumption. | Treatment includes adding a strong oxidant (chlorine, chlorine dioxide or ozone then filtration removal with proper sized mechanical filtration after sufficient contact time. |
| Lead | Lead is a highly toxic metal, and lead poisoning can be fatal. Lead occurs in water via dissolution from natural sources or plumbing containing lead (e.g. pipes, solder). Low pH water will cause lead pipes to leach. | Reverse osmosis Ion exchange Activated carbon |
| Magnesium | Magnesium is a dietary requirement for meat chickens. Magnesium occurs in water naturally from the weathering of rocks in the source waters catchment area, and it is a major contributor to water hardness. Magnesium itself does not negatively affect poultry health. However, it can cause scale build-up and negatively affect water lines and fogging systems. | Treatment the same as for hardness |
| Manganese | Manganese is a dietary requirement for meat chickens. It occurs naturally in water; usually low in surface water and higher in oxygen-depleted water (e.g. groundwater). Manganese itself does not negatively affect poultry health, and concentrations as high as 20mg/L has been reported not to affect bird health. However, it can negatively affect water lines and fogging systems (Batal, A. B. et al., 2005). High concentrations can give water a bitter taste that may decrease consumption. It has similar properties to iron but can be more challenging to remove due to the slower reaction time. | Reverse osmosis Ion exchange Aeration and filtration Oxidation and filtration Chlorination followed by filtration (most effective at pH of approximately 8.5, needs extended contact time with chlorine before filtration). |
| Potassium | Potassium is a dietary requirement for meat chickens. Potassium occurs in water naturally from the weathering of rocks in the source waters catchment area. Potassium itself does not negatively affect poultry health. However, it can cause scale build-up and negatively affect water lines and fogging systems. | Reverse osmosis |
| Sodium | Sodium is a dietary requirement for meat chickens. Sodium occurs in water naturally from rocks and soils in the source waters catchment area, as well as man-made sources. Concentrations vary greatly depending on geological conditions. High concentrations are more common in groundwater and certain catchments. | Reverse osmosis |
| Zinc | Zinc is a dietary requirement for meat chickens. It occurs in water via dissolution from natural sources or plumbing containing zinc (galvanised pipes and fittings, and brasses). | Reverse osmosis Ion exchange Activated carbon |
| Arsenic | Arsenic is a natural semi-metallic toxic element that is found all over the world in groundwater, from both natural sources and mining, industrial and agricultural wastes. | Reverse osmosis Ion exchange |
| Cadmium | Cadmium is a toxic heavy metal. In drinking water cadmium indicates industrial or agricultural contamination; from impurities in galvanised (zinc) fittings, solders and brasses. | Reverse osmosis Ion exchange |
| Cyanide | Cyanide is a highly toxic compound that can be produced from industrial waste and some plants and bacteria. | Activated carbon Reverse osmosis Oxidation |
| Mercury | Mercury is a toxic heavy metal. It can come from industrial emissions and spills or be naturally occurring (very low concentrations). Organic forms are the most toxic, but these are associated with biota, not water. | Activated carbon Reverse osmosis |
| Chloride | Chloride is a dietary requirement for meat chickens. Chloride naturally occurs in water from rocks and soils in the source waters catchment area, as well as anthropogenic sources. Concentrations vary greatly depending on geological conditions. High concentrations are more common in groundwater and certain catchments. | Reverse osmosis |
| Fluoride | Occurs naturally in some water from fluoride-containing rocks. It is often added to mains water at up to 1mg/L to protect against dental cavities. In levels greater than 1.5mg/L, it can cause human dental fluorosis. Greater than 4mg/L can cause human skeletal fluorosis. | Reverse osmosis |
| Nitrates | Occurs naturally as a result of the breakdown of organic matter. It is increasing in some water (particularly groundwater) flowing from intensive farming and sewage effluent. Studies observed no differences in meat chicken performance with nitrate levels as high as 600mg/L (Fairchild & Ritz, 2009). High concentrations are an indicator that water should be checked for microbial contamination. | Reverse osmosis Ion exchange |
| Sulphates | Natural component of water and may be added via treatment chemicals. Guideline value is taste threshold. Greater than 500mg/L can give meat chickens diarrhoea. | Aeration Ion exchange Reverse osmosis Oxidisation |
| Individual pesticides | Pesticides are substances that are used to control pests, including herbicides, insecticides, molluscicides, piscicides, avicides, rodenticides, bactericides, and fungicides (Randall et al., 2008). | Reverse osmosis Oxidation – depends on species Activated carbon |
| Total pesticides | The sum of pesticides in the drinking water sample. |
