Fine points of water testing

Done right, water testing is an effective way to verify water used on fresh produce is safe for use. Little things can have a big impact on this. Consider some fine points when taking water samples.

Verifying that irrigation water is safe for its intended use is of critical importance to fresh produce growers. Key to this verification is regular and effective water testing. When taking water samples to verify safety for fresh produce, a number of things need to be considered to ensure an accurate result.

Sanitize your hands

Opening a testing bottle exposes the very sterile inside of the bottle to a world of bacteria. Very large and often overlooked sources of bacteria are the hands of the person doing the sampling. It is therefore recommended that the person doing the sampling use hand sanitizer before opening the sampling bottle.

Save and use the preservative tablet

Most water sampling bottles have a preservative in the form of a tablet dropped into the bottle. When taking the sample, it is often easy to lose this tablet if it isn’t taken out first. After the water sample is drawn, it is essential to put the tablet back into the water sample. The preservative helps to maintain the accuracy of the testing being done.

Pay attention to the sample hold time and temperature it is held at

It is very easy to put off taking a sample into the lab until a much later, more convenient time. This must be avoided at all costs. In order for a water test to be considered valid, it must be delivered on ice to a lab within six hours of sampling. Anything longer or warmer than this can return false positive samples and higher than threshold results, increasing the cost of production.

Attention to the finer points of water sampling can not only ensure accurate samples, but can save you money. Having the confidence to use irrigation water without the use of disinfection treatment first can really add up in money saved with little loss of safety.

If you have difficulty with food safety issues, contact the Michigan State University Extension Agrifood Safety Work Group at or 517-788-4292. 

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