Introduction

The value of a clean, safe water supply is often overlooked in poultry production. Water tests performed by a reputable lab can be a valuable tool for identifying the source of performance problems. On-farm tests can also be helpful for monitoring and improving water quality. The following information was prepared as a guideline for interpreting poultry drinking water quality test results along with guidelines for commonly used correction options.

Bacteria Test

* Chlorine is the cheapest water sanitizer available and it works well, but other products such as chlorine dioxide and hydrogen peroxide are also available and used successfully.

The established guidelines for poultry drinking water quality are outlined in Table 1. Note that CFU/ml means colony-forming units of bacteria/millilitre of water, and mg/litre is the same as parts per million or ppm.

The test results received from some labs are labelled Total Plate Count (TPC) of aerobic ('oxygen-loving' bacteria as measured by CFU/ml. These results do not indicate whether the bacteria present is harmful (pathogenic) or harmless but it can indicate if the system is dirty and therefore at risk for the presence of harmful bacteria. If the TPC level is 1000 CFU/ml or less then the water supply is considered acceptable. However, the goal should be 0 CFU/ml even when the sample is pulled from the end of the drinker line. The closer water microbial results are to 0 CFU/ml, the better the water supply is for the commercial poultry production. Should the test results be greater than 10,000 CFU/ml, it is strongly recommended that the water system be thoroughly cleaned between flocks with an approved cleaner. After line cleaning, implement a consistent daily water sanitation program while birds are present.

Chlorine is the cheapest water sanitizer available and it works well, but other products such as chlorine dioxide and hydrogen peroxide are also available and used successfully. Drinking water target levels of free chlorine are 2-4 ppm, for chlorine dioxide the desired level is 0.8 ppm and for hydrogen peroxide, it is 25-50 ppm. (Table 2). Factors such as turbidity (suspended solids in the water; water actually looks dirty) minerals and organic material which is often present in surface water supplies will greatly influence how effective sanitizers work.

In addition, the dirtier the water, the more likely there will be taste issues associated with the use of chlorine. It is possible to see birds backing off water due to presence of high levels of chlorine, mainly when it is in the bleach form since bleach or sodium hypochlorite will have a bitter taste associated with it. When it becomes necessary to use more and more chlorine to get a 2-4 ppm free chlorine reading, then it is strongly recommended that the water be tested and a professional water treatment system installed. Chlorine dioxide and hydrogen peroxide are less likely to cause taste issues and are therefore good alternatives when treating some water supplies such as pond or river water supplies.

If the water test is performed by the Department of Health, the results are total coliforms. There are actually two types of coliform counts that may be reported. Total colform counts detect bacteria that can be found in many locations including feces, but fecal coliform counts detect bacteria that are found only in human or animal feces. Coliforms are a good indicator organism for potential contamination by livestock (runoff from concentrated animal production areas) or human waste (failed septic system). If total coliform counts are more than 50 cfu/ml and/or any faecal coliforms are detected, it is recommended that the well be 'shock-chlorinated'. However, shock chlorination can only be done to the water supply between flocks since the high level of chlorine is not suitable for consumption by humans or animals. In addition, look for possible sources of contamination and correct the problem to prevent recontamination.

Never assume that water quality remains good through poultry house water systems. When in doubt, test the water at the source and at the end of the line. Results from previous water tests (Table 3) show just how dramatically water quality can change even over the course of a few hundred feet.

Water supplies should be tested if there is:

• A noticeable change in colour, odour or taste
• Any flooding near the well
• A person or animal that becomes sick from waterborne disease
• Maintenance on water supply system
• Persistent poor flock performance or
• A loss of pressure in water system (Langston, 1994).

Mineral Tests

Pure water does not exist as drinking water. All water supplies have some amount of dissolved minerals or contaminants as they are referred to by EPA. In many cases, the contaminants are within acceptable ranges, cause no problems and may even be desirable. However contaminants present at unacceptable levels can potentially be linked to the following issues:

1. Poor performance
2. Equipment failure or damage or
3. Presence of harmful bacteria or fungal slime (some minerals serve as a food supply).

Information in Table 1 is listed as parts per million or milligrams per litre which is the same. Although ppm is a small amount, it is important to remember, the birds already receive a balanced diet and if they are also receiving high levels of such nutrients as salt in the water, in the form of sodium and chloride ions, then the birds may exhibit poor performance because they just have more than their systems can handle. In addition, several water contaminants such as iron and calcium can also impact how the drinker system functions. Even a fine build-up of mineral residue on seals or rims could be all that is necessary to limit water flow and thus result in less than adequate consumption for optimum bird growth and feed conversion.

On Farm Water Tests

While laboratory water tests provide valuable information, time is required for samples to be analyzed and critical decisions might be delayed. A good deal of valuable information can be collected on site using test kits or meters. This information can provide producers with a quick “score card” of how they are doing with respect to water quality. However, it is important to remember not to base major decisions on a single test. Two to three tests yielding similar results on similar samples will provide a more solid basis for decisions.

Oxidation-Reduction Potential (ORP) Meters

When developing water sanitation programs one tool that has proven useful in ensuring that water has optimum sanitizing value and quality for the birds is oxidation reduction potential (ORP). ORP simply refers to the property of oxidizing sanitizers such as chlorine to be their most effective. A strong oxidizer literally burns up viruses, bacteria and other organic material present leaving water microbiologically safe. An ORP value in the range of 650 millivolts (mV) or greater indicates good quality water that can be effectively sanitized by as little as 2-4 ppm free chlorine. The lower the value such as 250 mV indicates a heavy organic load or the presence of reducing agents such as ferrous iron, (Fe²⁺), manganese (Mn²⁺), bisulphide (HS^-) and sulphite.

Naturally occurring oxidizing elements in the water such as oxygen and sulphur along with chlorine and chromate can give increased ORP readings but it is usually only a good sanitizing residual at a favourable pH (5-7) that gives the most desirable ORP readings of 700- 750 mV. The ORP meter can be a useful tool for identifying water supplies that have inadequate chlorine residual and for adjusting the residual without overusing chlorine. A reliable ORP meter costs around $100 and can be purchased from Hanna Instruments, Hach or Grainger.

Chlorine Testing Kits

Chlorine test kits come in a variety of formats. The format is not as important as what is detected. Most inexpensive chlorine test kits (such as pool test kits) detect both free and total chlorine. Total chlorine does not distinguish between the chlorine that is bound and free or available chlorine. Only free chlorine is capable of water disinfection. A heavy organic load in it would result in a greater percentage of bound chlorine resulting in a poor sanitizer and possibly bad taste issues (decreased water consumption) even though the pool test kit might indicate total chlorine levels of 4 to 6 ppm. Therefore, be certain that the test kit detects free chlorine and that levels are 2 to 4 ppm.

pH Testing Kits

Kits for testing water pH are generally inexpensive and somewhat reliable. Birds are very tolerant of pH 2-3 for short periods, (2-3 days) and they are very tolerant of pH 4 to 8 on a continuous basis. Water sanitizers (chlorine, chlorine dioxide or hydrogen peroxide) generally work better when pH values are between 5.5 and 7. There is concern that some forms of strong acids (muriatic or phosphoric) or low pH (2- 3) can actually damage drinker equipment so before beginning any water acidification program, check the manufacturer’s recommendations.

Using Test Information

The bottom line: utilize information on pH, ORP and chlorine level to determine if the sanitation program is effective and to prevent equipment damage by the overuse of chemicals. It may also be valuable to record and retain the information collected so that trends can be seen.

Water Sanitation

Successful water sanitation programs start with a clean system. Once clean, there are several options for maintaining a clean system and providing birds with water that has sanitizing residual. These include chlorine, chlorine dioxide and hydrogen peroxide. Ozone systems are also used on poultry farms, but can be expensive to install for water sanitation alone. Iodine has also been used successfully as a daily water sanitizer. The guidelines in Table 2 can help growers assure they have adequate sanitizer present.

Water Treatments

Table 3 provides information on treatment options when contaminants are found at unacceptable levels. While there are many available treatment options, this section covers some of the basic treatments concepts. Before investing in any technology for water treatment, talk with a reputable water equipment dealer to assure the investment will fix your water quality issues.

Filtration

Water has many categories of impurities. The purpose of filtration is to reduce or remove the solid particulates and microorganisms from the water. Dissolved impurities can pass through filters. Think of it as filtering tea. The tea will taste the same before and after the filter but the tea leaves will be trapped by the filter. The benefits of reduced particulates and microorganisms in water on a poultry farm are several. Filtered water means that the drinker nipples do not clog or drip so the birds get water but the litter under the drinkers remains dry. This means, of course, that flocks grow rapidly due to increased hydration and fewer pathogens in the litter. Filtered water means less frequent clogs and better operation of evaporative cooling systems and therefore a healthier environment for the flock.

When used in conjunction with oxidation (described below) filtration can remove can remove dissolved minerals. Oxidation causes dissolved minerals to precipitate (settle) out, leading to higher particulate loads and problems with water lines, drinkers and cooling systems. However, when water is filtered after oxidation, particles and minerals are removed.

The retention of particles and microorganisms on filters is measured in microns. A micron is one millionth of a metre. A good reference point is 40 microns, which is the smallest particle the average human eye can see under optimal light conditions. The standard retention level for poultry house water systems is 20 microns. By far, the most common filter employed on poultry farms is the 10-inch long wound filter. While the filters are rated for 20 micron retention, they generally only retain 50% of the 20 micron particles, and that is only when a flow rate of 2 gallons per minute or less is passed through them. Higher flows cause channeling, where the water separates the windings and particles are pushed through. Also, these filters do not seal well to the filter housings, which can result in by-pass flow around the ends of the filters. To eliminate these problems, filters with O-ring seals and filter medias that retain 95% of the stated micron rating should be used (Hammond, 2008).

Oxidation

Oxidation is the process of reacting soluble minerals such as iron, manganese and sulphur with an oxidizer such as chlorine, ozone or chlorine dioxide or even air to create an insoluble particle that can be filtered from the water. One requirement for proper oxidation is to allow adequate time for the “oxidizers” to react with the minerals. To oxidize iron requires above pH7 and a minimum or 20 minutes reaction time while manganese needs above pH8 and much longer reaction time.

Water Softener

Water softeners are useful for removing calcium and magnesium as well as soluble iron and manganese. Water passes through a synthetic material or resin called zeolite where sodium is traded for these minerals. Sodium ions must be periodically replaced by flushing the softener tank with a solution of sodium chloride (salt). Most water softeners do not tolerate oxidized iron or manganese or iron bacteria. These must be removed first. If the water is cloudy, then some of the contaminants are not dissolved and must be removed first before the water softener.

Aeration

Aerating water can be effective for removing hydrogen sulphide, reducing dissolved carbon dioxide as well as oxidizing iron and manganese. This can be accomplished by pumping water into holding tank and allowing the water to fall into the tank like a waterfall instead of pumping water into a holding tank from the bottom.

Reverse Osmosis

Reverse osmosis (RO) is the most common option for reducing sodium, chloride and nitrates in water. In reverse osmosis, the water is forced by high pressure through a series of membranes. Water must be pre-treated to remove calcium, magnesium iron and manganese prior to the RO system. RO treated water can be aggressive or damaging to metal pipes and fittings.

Conclusions

Water is one of the most essential nutrient birds receive, yet the quality of bird drinking water is often taken for granted. Providing flocks with a clean and wholesome supply can make a difference in performance. Should water be a suspect for flock problems, make arrangements to have water tested for total bacteria numbers as well as for mineral content. While total aerobic plate count will not tell exactly what is in the water, it is an indicator of excessive levels of bacteria that should be addressed.

By promoting a regular water sanitation program on farm, producers can prevent environments in water systems that could lead to poor bird performance. Also understanding what types of chemical contaminants are present and addressing those that are known to cause poor performance can help growers improve their bottom line.

November 2008