Cleanliness and following instructions are important factors in testing equipment maintenance and procedures:

• Keep the reagent bottles, containers, vials, test tubes, comparators, dip cells, and hands clean and dry.

• Remove any spills and drips.

• Cross contamination between reagents caused by sloppy technique can cause problems before testing is even started.

• Get a fresh water sample in a clean container.

• Rinse the sample container with the water and get a sample from well below the water surface.

• Avoid sampling near water inlets and returns.

• Never test the water immediately after shocking or other chemical addition.

• When testing, follow the instructions carefully, including any specified waiting times.

• If adding drops of a reagent, hold the bottle vertically to get even sized drops.

• If doing a visual colorimetric determination (a color match), use a white or neutral color for a background. Use indirect light with your back to the sun.

• If using a colorimeter, run the test in the shade if possible.

• Avoid testing at the very top or the very bottom of a test range. These portions of the range often have poor accuracy.

• After testing, clean and rinse equipment and allow it to air dry.

• Store the test kit and reagents in a cool dry place.

• Periodically, test your kits against known reference standards recommended by the manufacturer.