How to Collect a Water Sample for Well Water Testing

Collecting a water sample for a laboratory water analysis is a critical step in the process of having your water analyzed. When collecting the samples, it is critical is to follow the directions outlined in the sample kit.

Something as simple as testing your hot water instead of cold, or testing the water that instantly comes out of the faucet instead of after two minutes can make a difference. A few simple steps and precautions taken during the collection process will insure that your sample will be accurately analyzed.

Avoiding Contamination
Water samples can be easily contaminated during the collection process if done incorrectly. Some of the steps to avoiding contamination include NEVER:

  • Rinsing the sampling bottle
  • Let water overflow or splash down the side of the bottle
  • Put the cap on a countertop (it can get contaminated)
  • Open the bottle until you are ready to collect your sample
  • Touch the inside of the cap, mouth, or neck of the bottle
  • Collect samples from a garden hose, outside tap, or other place that might be dirty

If you are testing for bacteria, avoiding contamination will be especially important to avoid false positives. Additional steps should be taken, including:

  • If collecting from a faucet, remove any aerators or filtration Collect Water Sample systems
  • Sterilize the faucet in order to eliminate any bacteria on the faucet
  • Sample from cold water, allow the faucet to flow for 2-3 minutes in order to clear the line
  • Fill only to the designated fill line (a sufficient “headspace” is required to properly mix the sample)
  • For an accurate bacteria test, it will have to be received by the lab within 24 hours. Overnight shipping is required and should not be shipped before the weekend or any holiday. Also, ship it with an ice pack to ensure valid bacteria results.

WaterCheck Lab Test Sample Collection Guidlines

If you are collecting a water sample for the WaterCheck test kits, here are some important instructions:

  • Wash your hands with soap and warm water.
  • Take the sample from a cold water tap. Use a tap without a screen or remove the screen before you collect the sample.
  • Let the cold water run constantly for at least 2 minutes before you collect the sample.
  • Hold the bottle near the base of the tap to get the sample. Fill it past the 200 mL mark (to the shoulder of the bottle). Do not overfill the bottle.
  • Put the cap on the bottle right away. Make sure the cap is secure, but do not over-tighten it.
  • If your test requires preservatives, do not forget to use them correctly
  • Put the identification label from the requisition form on the bottle.

Sampling Instructions

Fill out the requisition form and include the information below. If you miss anything on the requisition, your sample might not be processed.

  • Name and daytime phone number
  • Mailing address and postal code
  • Collection site (e.g., kitchen sink)
  • Legal land description and/or civic address
  • Date and time sample was collected
  • Name of person who collected the sample

On the requisition form, write down if this is a re-sample. You also need to fill out section A (Drinking Water) and add any comments or special requests at the bottom of the requisition.

  • Put the sample and requisition form in the plastic bag that came with the sample bottle.
  • Put the sample in a cooler filled with ice packs and bring it to a drop-off location near you right away, or if sending by express, use overnight next day morning option.

Thanks for reading!

About the Author Gerry Bulfin

Need help with your well water? I have been assisting homeowners, small communities and businesses improve their well water quality since 1989. Please email me at if you have a question about water testing, test kits or well water systems in general. Gerry Bulfin CWS-IV Master Water Specialist WQA Certified Licensed California Water Treatment Contractor