How to collect a well water bacteria sample (step by step)
These steps follow Penn State AASL's instructions for its kit. Always follow your own lab's instructions, since bottles and holding times vary. [source]
- Use only the sterilized bacteria bottle (Penn State's has a green label). If it contains a small white pill or powder, leave it in.
- Choose an inside faucet and remove the aerator.
- Run the cold water for about five minutes to purge the plumbing.
- Remove the lid holding only the outside of the cap. Don't touch the inside of the bottle or cap.
- Fill to the 100 mL line and screw the lid on tightly.
- Refrigerate until shipping.
- Get it to the lab within 30 hours of collection. Penn State also requires arrival no later than Thursday of the week. [source]
Lead is different
Penn State's first-draw lead sample is the opposite: collect the first water out of the kitchen faucet in the morning after it has sat at least six hours, without running it first. [source]
The EPA also advises asking the lab for instructions and sample bottles before sampling, and testing again after replacing or repairing any part of the well system. [source]
FAQ
How long can a well water bacteria sample wait?
Penn State AASL requires bacteria samples to reach its lab within 30 hours of collection. Check your lab's holding time.
Sources
- Penn State AASL – How to Collect a Water Sample (accessed 2026-10-21)
- US EPA – Protect Your Home's Water (accessed 2026-10-21)
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