Science of Water : Concepts and Applications

Environmental Biomonitoring, Sampling, and Testing 247
3. Precision and accuracy of available monitoring equipment
4. Capabilities of monitors
Note: We discuss the parameters most commonly monitored by drinking water practitioners in
streams (i.e., we assume, for illustration and discussion purposes, that our water source is a surface
water stream) in detail in this section. They include DO, BOD, temperature, pH, turbidity, total
orthophosphate, nitrates, total solids, conductivity, total alkalinity, fecal bacteria, apparent color,
odor, and hardness. When monitoring water supplies under the Safe Drinking Water Act (SDWA)
or the National Pollutant Discharge Elimination System (NPDES), utilities must follow test procedures
approved by the USEPA for these purposes. Additional testing requirements under these and
other federal programs are published as amendments in the Federal Register.
Except when monitoring discharges for specifi c compliance purposes, a large number of
approximate measurements can provide more useful information than one or two accurate analyses.
Because water quality and chemistry continually change, periodic, representative measurements and
observations that indicate the range of water quality is necessary, rather than testing the quality at
any single moment. The more complex a water system, the more the time required to observe, understand,
and draw conclusions regarding the cause and effect of changes in the particular system.
GENERAL PREPARATION AND SAMPLING CONSIDERATIONS *
Sampling devices should be corrosion resistant, easily cleaned, and capable of collecting desired
samples safely and in accordance with test requirements. Whenever possible, assign a sampling
device to each sampling point. Sampling equipment must be cleaned on a regular schedule to avoid
contamination.
√ Note: Some tests require special equipment to ensure the sample is representative. DO and
fecal bacteria sampling require special equipment and procedures to prevent collection of nonrepresentative
samples.
Reused sample containers and glassware must be cleaned and rinsed before the fi rst sampling
run and after each run by following Method A or Method B described below. The most suitable
method depends on the parameter being measured.
Method A: General Preparation of Sampling Containers
Use the following method when preparing all sample containers and glassware for monitoring conductivity,
total solids, turbidity, pH, and total alkalinity. Wearing latex gloves:
1. Wash each sample bottle or piece of glassware with a brush and phosphate-free detergent.
2. Rinse three times with cold tap water.
3. Rinse three times with distilled or deionized water.
Method B: Acid Wash Procedures
Use this method when preparing all sample containers and glassware for monitoring nitrates and
phosphorus. Wearing latex gloves:
1. Wash each sample bottle or piece of glassware with a brush and phosphate-free detergent.
2. Rinse three times with cold tap water.
3. Rinse with 10% hydrochloric acid.
4. Rinse three times with deionized water.
* The sections that follow detail specifi c equipment considerations and analytical procedures for each of the most common
water quality parameters.