25 May 2005
Each water analysis requires specific chemical apparatus. These are scientific
instruments and are to be treated as such. The apparatus will last indefinitely if given
proper care. All equipment and apparatus, especially glassware, should be kept clean.
Unless this is done, the tests will not be reliable and errors will be introduced.
Thoroughly rinse and air-dry all glassware immediately after use. If color apparatus is
employed, do not expose to heat or direct sunlight. If any liquid is spilled on any of the
equipment or apparatus, wipe off at once and dry.
Testing Procedures. The suspended matter or sludge will generally settle
to the bottom if the sample is allowed to stand before testing. The clear water can then
be used for the tests, making it unnecessary to filter (except for specific tests).
Theoretically, all water analyses should be made at 25 oC (77 oF); however, no
appreciable error will be introduced if the test is made between 20 to 30 oC (68 and 86
F). In general, the shorter the time between the collection and analysis of the sample,
the more reliable the results will be.
When the water sample color interferes with the analysis, it may be necessary
to filter the sample through activated charcoal. NOTE: This does not apply to the sulfite
and nitrite tests.