The Correct Procedures in Preparing Water Sample for Testing

Have you ever been concerned about your home water? If you are not satisfied with your water, you can simply bring the water sample to the local water lab, water-related business and see the detailed components of your water.

It is worth noticing that regardless of where or how analysis is performed, there are certain precautions that should be observed in preparing a water sample for shipment to a laboratory. Careless handling of a sample can produce highly misleading results.

lab equipment

To achieve valid results, the following steps should be taken:

  • Secure a container (16 oz. size preferable) of a type that will not permit contamination of the sample. Clean rubber stoppered, resistant glass bottles or polyethylene containers are recommended. A plastic screw-capped bottle may be used. It is advisable to use a new bottle for each test. If this is not possible, the bottle and cap should be washed in soap and water and thoroughly rinsed before use.
  • Before taking samples through metal lines and valves, first, allow sufficient flow of water to wash out the system.
  • Rinse the container thoroughly. Use the water that is to be analyzed for this purpose.
  • Fill the bottle to a point just below the shoulder. Leave just a little air space.
  • Immediately after filling the container, jot down all pertinent information regarding the water at the time the sample is taken. Facts to include: source of the sample; physical appearance of the water (clear, dirty, highly colored, etc.); odor, if any; taste as reported by the homeowner, if any.
  • Do not take the sample from a swing-type faucet. Inspect the faucet for leaks. Select another faucet if there is leaking. Disinfect the faucet with bleach or a flame.
  • Send the sample to the lab for testing.
  • If needed, store the sample in the refrigerator before taking it to the lab.

A water sample needs to be submitted to the lab within 48 hours of collection. In some cases, it must be kept cold prior to testing. Care must be taken to prevent anything but the water from contacting the inside of the bottle or the cap. Contaminants are often present in small amounts. Careless sampling prevents accurate test results.

Testing for Volatile Organic Chemicals

When collecting a sample to be tested for volatile organic chemicals these additional steps should be followed:

  • Reduce water flow to prevent excess air in the sample.
  • Remove all air from the collection bottle by filling it to almost overflowing. Again, timeliness and cleanliness are extremely important to prevent false results.
  • Testing for Pesticides

Samples for pesticide testing must be taken so they will not deteriorate or become contaminated before reaching the lab. Contact the lab testing the sample for complete instructions and a collection kit. Specific steps needed when testing for pesticides include:

  • Collect the sample only in the amber-colored bottle provided. The dark glass prevents light from degrading the sample.
  • Cap the bottle with the Teflon-coated lid. The special lid prevents false-positive results caused by certain plastics.
  • Keep the sample refrigerated, preferably 35 degrees to 38 degrees, and submit it to the lab within 48 hours. If shipping the sample, pack the sample in ice and ship in a Styrofoam or other insulated container.

Is a "complete" water analysis necessary in every case? Definitely not! In many cases, a "complete" analysis would be unwarranted. Where an unusual situation exists, it is perhaps wise to make a "complete" analysis of the water. Such tests when completed would give information on such chemical contaminants as those listed in the EPA Interim Primary Drinking Water Regulations, and others such as alkalinity, sodium, sulfates, chlorides, tastes, odors, turbidity, and color in addition to hardness, iron, pH, etc.

After a water analysis has been made, there is still a need for corrective action.

Sound treatment is a matter of judgment based on know-how, experience, and the particular requirements of the individual owner in each case. Often a water analysis will reveal conditions that might be treated in one of several possible ways. In many cases, there may not be anyone the best possible answer. Several solutions may be satisfactory depending on the factors involved.

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