Drinking Water Monitoring - The Drinking Water - page 223

reference for shades typically found in natural waters and can also be used
for its original purpose—describing the colors of insects and larvae found in
streams or lakes. The Borger Color System also allows the recording of the
color of algae and bacteria on stream beds.
Note: Do not leave color standard charts and comparators in direct
sunlight.
Measured levels of color in water can serve as indicators for a number of
conditions; for example, transparent water with a low accumulation of dis-
solved minerals and particulate matter usually appears blue and indicates
low productivity. Yellow to brown color normally indicates that the water
contains dissolved organic materials, humic substances from soil, peat, or
decaying plant material water. Deeper yellow to reddish colors in water indi-
cate the presence of some algae and dinoflagellates in the water. Water rich
in phytoplankton and other algae appears green. A variety of yellow, reds,
browns, and grays is indicative of soil runoff. To ensure reliable and accu-
rate descriptions of apparent color, use a system of color comparison that is
reproducible and comparable to the systems used by other groups.
odor
Odor in water is caused by chemicals that may come from municipal and
industrial waste discharges or natural sources such as decomposing veg-
etable matter or microbial activity. Odor affects the acceptability of drinking
water, the aesthetics of recreation water, and the taste of aquatic foodstuffs.
A wide variety of smells can be accurately detected by the human nose,
which is the best odor-detection and -testing device currently available. To
measure odor, collect a sample in a large-mouthed jar. After waving off the
air above the water sample with your hand, smell the sample. Use the list of
odors provided in Standard Methods (a system of qualitative description that
helps monitors describe and record detected odors; see Table 10.6 ) to describe
the smells. Record all observations.
Summary
All of the elements that comprise the standard practices associated with
proper water monitoring provide drinking water practitioners with the tech-
nical and scientific data necessary to determine the level and types of treat-
ment required to successfully condition water obtained from surface and
groundwater sources. We cover drinking water treatment in Chapter 11 .