(EPA Methods 515.1, 525.2, 531)

Herbicides, Pesticides, Adipate, PAHís, Carbamates, Glyphosate, Paraquat & Diquat






                    Samples must be collected in the proper number, at the appropriate time and location, and of the proper volume in order to satisfy the requirements of the Phase II and Phase V rules.Samples that fulfill these criteria are called compliance monitoring samples.Groundwater and surface water systems should be representative of the source water following treatment (See figure on the back of this sheet).Systems that draw water from more than one source and that combine these sources prior to distribution must sample during periods of normal operating conditions.Samples must be collected at the same sampling point each cycle unless conditions make another sampling point more representative.Generally, samples should be taken at the tap on the pipeline before the treated water is sent to the distribution system.If the water system is treating for any organic compounds (i.e. packed tower aeration, granular activated carbon, oxidation, etc.) contact your regional Drinking Water Specialist to locate the proper collection point.You will find the name and telephone number on the back of this sheet.


                    Bottles must NOT be filled near gasoline cans, gasoline-powered motors, paint cans, lighter fluid, paint strippers, pesticide bottles or exhaust fumes from running engines.Fumes and vapors may contaminate the samples.


Click here for examples for determining sampling locations and numbers of required samples (applies to all Phase II and V contaminants except asbestos tap sampling and acrylamide/epichlorohydrin.)


If you have any questions about sampling locations, remember to call your Washington State Drinking Water Specialist:




1)      If water taps are to be used for sampling, all aerators, strainers and hose attachments need to be removed.Open the tap and allow the system to flush for about ten minutes or until the water temperature has stabilized.Adjust the flow to about the thickness of a pencil.Position the container under the tap and collect the sample.Introduce the water very gently to reduce agitation and to avoid introducing air bubbles.Fill the bottle so that little or no air space will remain in the bottle after the cap is secured.


2)      Collect __2___ one-liter bottle(s) at each collection point for method 525.2

Collect __2___ 500 mL bottle(s) at each collection point for method 515.2

Collect __1___ 250 mL bottle(s) at each collection point for method 531


IMPORTANT: Be careful not to touch or otherwise contaminate the inside of the lid or the lip of the bottle during sampling.


3)      All samples need to be kept cold.If the samples are to be held for a day or longer prior to shipping, place the bottles in a refrigerator.Once samples are ready to be shipped, add a bag of ice to the cooler.Samples must be received at Twiss Analytical Laboratories, Inc. within two (2) days of sampling.

4)      Insert the completed sample information form (WSI) into a plastic bag and place in the cooler along with the samples.


Please contact Twiss Analytical Labs at (360) 779-5141 if you have any questions.