c. Use of and Method for the Kit. Procedures to test water for proper
chlorination are listed below.
(1) As with the original chlorination kit procedures, prepare a stock solution
by mixing and dissolving the contents of one or more calcium hypochlorite ampules,
depending on the quantity of water to be chlorinated, in a small, separate container of
water. The stock solution is then poured into the container that houses/holds the water
(such as a 5 gallon water can) to be disinfected. The water is stirred with a clean stick.
If faucets are present, they should be flushed with a small quantity of water.
(2) After waiting 10 minutes, draw water to fill the DPD color comparator
above the tip of the uppermost black border. Flush tap and rinse the color comparator
Tear open one DPD tablet package and drop the tablet into the
(4) After waiting 2 minutes, place the thumb over the opening of the
comparator and invert it 3 times to mix the water and tablet contents.
(5) It is now time to compare the color of the chlorinated water with that of
the comparator color. If the color of the water in the left window marked one is the
same or darker than the right window marked one, the chlorination is acceptable for the
water. However, wait an additional 20 minutes before drinking or using the water and
compare the colorations again. If the color of the water is lighter than the window
marked one, repeat chlorination and testing. See (6) below.
(6) When comparing the chlorinated water that was obtained directly from
untreated sources (streams, lakes, springs, wells, and so forth), compare the window
marked five with that of the comparator marked five. If the color of the water in the left
window marked five is darker than the right window, chlorination is acceptable.
However, wait an additional 20 minutes before using the water. If the color of the water
is lighter than the window marked five, repeat chlorination and testing. (The lighter
water means there is not sufficient chlorine residual to maintain disinfected water
When testing water with the DPD color comparator, carefully observe the
color changes of the water. When the chlorine residual is above10 mg/I,
the water color will change through the comparator level sand then turn
clear. Failure to carefully observe the color changes may lead to an
excessive amount of chlorination. Too much chlorine in the water may be
just as harmful as too little.