Sample carefully to insure that your analytical results will present the actual sample composition.
Distribution Systems - Flush lines sufficiently to insure that the sample is representative of the supply.
Wells - Pump well sufficiently to insure the sample represents the ground water source.
River or Stream - If equipment is available, take an integrated sample from top to bottom in the middle of the stream in such a way that the sample is composited according to flow. If only a grab sample can be collected, take it in the middle of the stream at mid-depth.
Lakes and Reservoirs -Choose location, depth, and frequency of sampling depending on local conditions and the purpose of the investigation. Avoid surface scum.
Use 1 - liter polyethylene bottle for collecting water samples. Before filling, rinse sample bottle out two or three times with the water being collected. Fill bottles completely and cap tightly. Avoid sample agitation and prolonged exposure to air. Have samples analyzed without delay,preferably within 1 day. To aid preservation, keep samples under refrigeration. Identify every bottle by attaching an appropriately inscribed label. Complete record form.
Types of Samples
Grab Samples - A sample collected at a particular time and place representing only the composition of the source at that time and place. If the source is known to be fairly constant in composition, then the sample may represent a longer time period or larger volume than the point at which it was collected. If the source is known to vary with time, grab samples collected at suitable intervals can document these variations. If the source varies in space rather than time, collect samples from appropriate locations.
Integrated Samples - A mixture of grab samples collected from different points simultaneously, or as nearly so as possible.