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By Robert Curran, Water Quality Engineer
 As evidenced by the mere fact our customers purchase water purification and distribution equipment, water quality is an important factor in animal facilities. Contaminated water not only affects animal health, but also the validity of the research being conducted. For this reason, even after a facility has invested in a top of the line water purification and distribution system, periodic water testing should be performed to ensure that the equipment is meeting the required standards. However, proper sampling, preservation, and measurement techniques are of paramount importance to obtaining accurate, consistent results that yield a realistic picture of your water quality.
There are three basic categories of water contaminants that should be checked on a periodic basis. They are Inorganics, Organics, and microbiological. The sampling technique for each of these is the same, with the one obvious exception being microbiological samples need to be collected using aseptic techniques, where as the inorganic and organic material do not require aseptic techniques (Appropriate aseptic sampling procedures will be discussed later). The best resource for information regarding water sampling is the “Standard Methods for the Examination of Water and Wastewater” published jointly by the American Public Health Association, American Water Works Association, and Water Environment Foundation. Section 9060 outlines the industry standard for proper sampling techniques. This is a fairly in-depth chapter, covering a wide variety of water sources, but the general principles are the same throughout.
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"Contaminated water not only affects animal health, but also the validity of the research being conducted. Periodic water testing should be performed to ensure that contaminants are not present in the water."
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Containers used to collect samples must be cleaned, preferably with distilled lab grade water. This is to remove any residual contamination in the container that may show up on the water analysis. Second, the sample port should be allowed to flush for 15-30 seconds prior to collecting the sample. This will allow any contaminants that may have collected in the valve to be removed, providing a more representative sample of what is actually in the system. After the sample port has flushed, remove the cap of the sample bottle, fill the bottle to about 3/4 full, and immediately recap. The bottle should only be filled 3/4 full to allow for mixing prior to being analyzed. One exception to this is when sampling for Volatile Organic Chemicals (VOCs). If you are testing for VOCs there should be a bottle dedicated to that sample and it should be filled as completely as possible. As the name indicates, these samples contain organic material that is volatile, or wanting to escape into the air. If you leave an air space in the bottle, these VOCs will leave the water and move into that air space. When the bottle is opened, they will escape and the results of the tested water will be invalid. Once samples are collected, they should be placed on ice, or chilled in some other fashion until analysis can be performed.
Aseptic techniques are required when performing bacterial analysis, but are fairly basic. Collection bottles should be autoclaved prior to use. The lip or inside of the bottle should not contact anything after being sterilized. The sample port should be cleaned using ethanol or bleach and allowed to sit for 1-2 minutes prior to flushing the valve to kill any bacteria present on the valve. If the water is chlorinated, Sodium Thiosulfate should be added to the sample to remove the chlorine. This will prevent the chlorine from killing the bacteria after sampling but prior to analysis. Otherwise, microbiological samples should be collected in the exact same way as other samples.
Once your samples are collected they need to be analyzed. It is far and away easiest and cheapest to have the organic and inorganic samples analyzed by an outside lab. Typically these analytical labs will send you a test kit containing all of the necessary sample bottles, an instruction sheet, an ice pack, and an insulated package for their return trip. The sample bottles will be pre-cleaned and contain a preservative. DO NOT clean or remove this preservative. It is there to stabilize the sample for the trip to the analytical lab and is necessary to receive accurate results. With these kits, follow the instructions provided. Results are often available 1-2 weeks after they are received at the lab. We normally use and recommend National Testing Labs (www.ntllabs.com), but there are several choices available. For microbiological samples, time is of top importance. Since the bacterial growth rate is exponential, waiting for samples to be shipped to an outside analytical lab can skew results dramatically. For this reason we recommend plating samples in-house whenever possible. We suggest using a Hetrotrophic Plate Count (HPC) or R2A media. Simply place 1 mL of the sample on the plate, allow it to be absorbed into the media, and allow it to incubate for 48 hours at 37ºC for the HPC media or 7 days at 25ºC for the R2A media. At that point count the colonies and that will be the CFU/mL (colony forming units per milliliter) for that sample. There are other methods available that promise quick results, sometimes in minutes. However, we have yet to find one of these tests that is based on a proven technology, have received regulatory approval by the FDA or EPA, or have sensitivities less than 1000 CFU/mL, therefore we recommend exercising extreme caution if using one of these systems. The results they provide can be very misleading. The old adage “If it's too good to be true, it probably is” also applies to microbiological testing. If you are currently using one of these technologies and have a question about it, please feel free to contact us. We will be happy to research it for you.
In order to gain an accurate representation of your water's quality and the performance of your purification systems, follow the above procedures when testing your water. Water should be checked for organics and inorganics every 4-6 months, and checked for microbiological contamination every 1-4 weeks. If unexpected results are found, feel free to contact Edstrom Industries, and we will be happy to assist in tracking down the problem.
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