How to collect a well water sample: bacteria, first-draw lead, radon and more

The short answer: get the bottles and the instruction sheet from the state-certified lab that will run the test, and collect on the morning you ship or drop off. Fill the first-draw lead bottle first, before anyone uses that faucet. Then run the cold water and fill the rest: bacteria into a sterile bottle you never rinse, radon and VOCs into small glass vials with no air bubble, PFAS into a plastic bottle filled only to its line. Each test has its own container, preservative and clock, and the table below puts all eight side by side.

Most sampling sheets online come from one county or one lab and cover one test, usually bacteria. This page lines up the federal rules for public water systems (40 CFR 141.23, 141.852 and 141.86) with the sheets of state laboratories that publish one per test, mainly Vermont's and Minnesota's, and says why each step is there.

Every well test in one table: bottle, preservative, clock and reason

The federal time limits were written for public water systems. Montana State University's Well Educated program says plainly: "There are no hold time requirements for private well samples." Labs still set their own limits and reject samples that miss them, so the time column is the deadline you actually have to meet.

Sources: 40 CFR 141.23(k)(2), 40 CFR 141.852, 40 CFR 141.86; Vermont Department of Health Laboratory kit sheets from its forms page (updated October 30, 2026); Minnesota Department of Health Sample Collection Procedures (updated October 1, 2026); Wisconsin State Laboratory of Hygiene; EPA Radionuclide Basics: Radon.

Minnesota's procedures are written "for Safe Drinking Water Act compliance at public water systems," so they ask for duplicates and blanks a homeowner kit may skip. Vermont's sheets are written for homeowners. Even within Minnesota's set, the clocks run from 30 hours to 28 days, and to 6 months for an acid-preserved arsenic bottle:

The day before: what to set up

• Freeze the ice packs. Minnesota says at least 48 hours ahead. Vermont wants chilled samples below 42 °F (6 °C), "cold, but not freezing." Both labs reject frozen samples.
• Pick the day. Vermont's bacteria sheet says not to mail on Fridays or the day before a state holiday; Minnesota's coliform procedure says to collect and ship only on a Monday, Tuesday or Wednesday.
• Leave the lead faucet alone overnight. Vermont's lead sheet: "Do not flush the faucets prior to letting the water sit for 6 hours."
• Wait out any chlorine. Vermont's VOC kit says to run the water until the chlorine smell is gone "and then wait two more days before testing," and Vermont's acceptance policy lists "chlorine or other oxidizers are present" among the situations that "will likely result in the sample being rejected." The shock chlorination guide covers when the bacteria retest follows.

Two tests add a personal checklist. For VOCs, Vermont asks you not to pump gas or handle volatile chemicals that day and not to use hand sanitizer first: "This test is SENSITIVE to these types of activities." For PFAS, Minnesota bans sticky notes, stain-resistant clothing and disposable cups during sampling, wants a ballpoint rather than a permanent marker, and asks for washed hands if you've handled foods sold in PFAS-treated wrappers such as fast food that day.

Which tap: the well, or what you drink?

The tap decides what question the result answers. Penn State Extension says most samples are taken at the kitchen faucet, which "will often be influenced by the treatment equipment," and that for raw well water you may want the spigot on the pressure tank. North Dakota State University (NDSU) Extension prefers a raw sample and says a second one after the equipment "will help you determine if your equipment is functioning properly." Vermont's uranium sheet gives both options: before treatment "to check the water from the well," after it "to check the treated drinking water."

For bacteria, some faucets are poor choices. South Dakota's bacteria sheet, written for public-use sampling points, prefers a non-swivel faucet, avoids one that leaks "as leaking faucets can promote bacterial growth," and rules out frost-free faucets and taps after carbon filters or softeners. University of Arizona Extension says not to choose a faucet that "swings or leaks." Whatever you pick, write it down, and if you bypassed treatment, Vermont asks you to write "bypass treatment" on the form.

First-draw vs. flushed: two samples, two questions

Vermont's lead instructions define both. A draw sample "will show how much lead/copper has leached (dissolved) into water that has been in the pipes" for at least six hours. A flush sample, from the same faucet after 3 to 5 minutes of cold water at full flow, shows "whether flushing the lines is sufficient to reduce lead/copper levels" and, for a private supply, draws on "the line coming from the well or spring." How long the water must stand first depends on who wrote the sheet:

The aerator stays on because it is part of the water path: EPA's lead page says "sediment, debris, and lead particles can collect in your aerator." Vermont's package says the first-draw bottle "must be filled first"; water run earlier from that faucet would carry away the standing water the test measures. Put the open bottle under the faucet before turning it on, then open the cold tap slowly, as you would to fill a glass (Vermont). What a high first draw with a clean flush means, and the reverse, is in the decision table on our lead in well water page.

Bacteria sample, step by step

These steps follow Minnesota's total coliform procedure, with other labs' numbers where they differ.

1. Take everything off the faucet: "aerator, screens, washers, hoses, water purification devices."
2. Optionally, sterilize the spout: flame the edge "for at least 15 seconds or wipe edge with an alcohol wipe." Never flame a plastic faucet.
3. Run the cold water 4 to 5 minutes (Minnesota) or 3 to 5 at high flow (Vermont, which adds: on a single-handle faucet, hot for 2 minutes, then cold for 2). Mississippi State University Extension says 2 minutes at full force.
4. Turn it down to a small, smooth stream without shutting it off. Don't touch the inside of the cap or bottle.
5. Don't rinse the bottle. What's inside "is a dechlorinating agent."
6. Fill to the line. "Too little or too much water will result in sample rejection." Vermont's 100 mL bottle may be filled to the neck.
7. Cap, label, chill (cool, not frozen), and record the date and time.

The sterilizing step has a catch that Arizona Extension spells out: "by sterilizing the faucet with a flame, you could be removing a source of bacterial contamination." A cleaned spout tells you about the well and plumbing; an uncleaned one tells you about the water as it reaches your glass. After a positive result, a second sample from a cleaned faucet is one way to tell the two apart.

Then the clock. Montana State says coliform tests "only identify the presence of bacteria if they are alive in the sample," that results are more reliable within 30 hours, and that past 48 hours they "are likely not reliable." Lateness errs one way: a late "Present" is still a real positive, a late "Absent" may only mean the bacteria died in transit. Extension guidance on the ideal window varies: Penn State says within 24 hours, NDSU 36, and Arizona says it is best within 6 hours, with some labs allowing 12. Our coliform bacteria page covers what each result means.

Radon in water: no headspace, no delay

Radon and VOCs are the tests a single air bubble can end. EPA describes radon as "an odorless, colorless, radioactive gas" with a half-life of 3.8 days, so the vials must be completely full and must reach the lab fast. The Vermont Department of Health Laboratory's Kit RC sheet (version 7.0):

1. Remove the aerator if possible. Don't touch the inside of the cap or the vial's mouth.
2. Run the cold water at full flow for 3 to 5 minutes, then turn it to low flow.
3. Fill both 40 mL vials "until overflowing," from the same tap, and cap them tightly.
4. Turn each over and tap it. "If air bubbles of any size are present, dump out the vials and repeat sample collection."
5. Record the date and time, wrap the vials in paper towels, and get them to the lab within 48 hours.

The Wisconsin State Laboratory of Hygiene lists no preservative and a 4-day limit. No chemical slows radioactive decay, so speed is the only protection. The sheets don't explain the bubble rule; the likely reason is that a dissolved gas can move into any air space in a sealed vial, and the VOC vials below follow nearly the same rule. Penn State Extension adds that some rare, specialized tests, radon among them, "usually require that a lab employee visit your home to collect the sample," so ask who samples before you order. Results are explained on our radon in well water page, treatment in radon in water mitigation, and labs are in the radon lab finder.

VOCs and PFAS: the two tests you can contaminate yourself

VOCs: a dome of water and a trip blank

VOCs evaporate (see our VOC page), so their vials are filled like radon vials. Minnesota asks for a pencil-width stream, the vial at a slight angle, and filling "to form a convex meniscus above the top of the vial," topping up with the cap if needed. Cap, turn over, tap. Per method requirements, Minnesota's lab rejects samples with "any air bubbles greater than 6 mm in diameter at the time of analysis." Vermont's vials contain "a small amount of HCl" (hydrochloric acid; it recommends gloves and safety glasses), and its sheet says not to empty or overfill a vial because "the preservative will be lost."

The trip blank is the vial you never open. Minnesota says trip blanks "must accompany the target analyte samples throughout the entire trip." If a compound turns up in both, the lab flags it (code B6: "The analyte was found in both trip blank and sample"), because it may not have come from your well.

PFAS: the line on the bottle and a field blank

Minnesota's PFAS procedure (listed October 2026; the PDF footer reads September 2026) uses a 250 mL HDPE bottle with about 250 mg of ammonium acetate, filled only to between the 7 oz and 8 oz marks: "Overfilling will result in rejection of samples." Wear powder-free nitrile gloves, run the cold water 4 to 5 minutes, and get the bottles into a cooler within 15 minutes. The field blank is reagent water from the lab that you pour into an empty bottle at the sampling point, logged with the same date and time as the sample. Minnesota's clothing rule shows how strict PFAS sampling can be: "old, well-laundered (at least six washings since purchase) clothing," washed without fabric softener. A homeowner kit may ask for less; if it's silent, Minnesota's list is a cautious default. Rules and reporting limits are on our PFAS page.

Nitrate, arsenic and uranium: the longest clocks

Inorganic chemistry is the most forgiving group, if the bottle is preserved. EPA's table gives arsenic and most metals 6 months with nitric acid and nitrate-nitrite 28 days with sulfuric acid, against 48 hours for plain chilled nitrate. It adds that "in all cases samples should be analyzed as soon after collection as possible," and lets metals samples be acidified at the lab instead of at the tap, provided the shipping time and method instructions are followed. That's why some kits arrive without acid, and why those bottles have a short deadline: Minnesota gives an unpreserved arsenic bottle 14 days.

In the lead rule, EPA describes acidifying "to resolubilize the metals," after which the sample must "stand in the original container." Vermont, separately, lists a sample "collected in a different container and transferred to laboratory containers" among those likely to be rejected. Fill the lab's bottle directly at the tap.

Uranium shows one test on three clocks. Vermont's Kit RU (EPA method 200.8) asks for a 1-liter plastic container, aerator removed, cold water run "5-10 minutes," and receipt within two days. Wisconsin's state lab gives an acidified gallon 6 months but an unpreserved one 5 days; Minnesota asks for 4 L, unpreserved, within 5 days. Vermont's homeowner inorganic kit C has two bottles, the first after 8 to 18 hours without use, the second after 3 to 5 minutes of running, and must reach the lab within 48 hours, chilled. For results, see the uranium and nitrate pages (check "as N" vs. "as NO₃" before you worry).

A morning order that keeps every bottle valid

Vermont's package fixes only step one: the first-draw lead bottle first, then the rest "can be filled in any order." One sequence that respects every sheet above, at one faucet where you can:

1. First-draw lead (and the first bottle of an inorganic kit such as Vermont's Kit C): aerator on, first water out.
2. Flushed lead (and the second Kit C bottle): aerator still on, cold water run 3 to 5 minutes at full flow first (Vermont).
3. Remove the aerator and keep the cold water running for the longest flush your remaining sheets ask for: 5 to 10 minutes if uranium is in the kit, otherwise at least 5 minutes or until the water is as cold as it gets.
4. Other chemistry bottles (nitrate, arsenic, uranium) at medium flow.
5. Bacteria at a small, steady stream.
6. VOC and radon vials last, at the lowest flow, each checked for bubbles.
7. Write every date and time, pack the bottles with frozen ice packs, and ship or drive them the same day.

This order is our synthesis, not a lab rule. If your lab's sheet differs, follow it.

Why labs reject samples

Vermont's Drinking Water Sample Acceptance Policy (version 6.0) says the sampler "is responsible for following the sampling instructions," and lists what "will likely result in the sample being rejected":

Who may collect the sample for a home sale, loan or dispute

For a routine test, you can. Penn State Extension: "In most cases, homeowners can collect water samples themselves, after obtaining proper sanitized containers and instructions from the laboratory."

A loan can take that away. VA Pamphlet 26-7, Chapter 12 (Topic 16) says: "All testing must be performed by a disinterested third party. This includes collecting and transporting the water sample from the water supply source." It may be "the local health authority, a commercial testing laboratory, a licensed sanitary engineer, or other party that is acceptable to the local health authority," and "at no time will the Veteran or other interested party collect and/or transport the sample." FHA's matching third-party rule and USDA's rule on who must analyze the water are quoted, with dates and report age limits, in our FHA, VA and USDA well water test guide. Ask your lender before anyone fills a bottle.

Some states add their own rule. New Jersey's Private Well Testing Act requires testing of raw water when a home with a well is sold, and the state health department points to labs "certified for private well sampling" (NJ fact sheet, updated January 2023). Where a result might end up in court, Penn State says samples "should be collected by a disinterested third party," which "will be vital to the admissibility of the results in any legal action," for example before gas drilling nearby. That case is covered in fracking and well water testing.

Before you seal the cooler

Vermont's acceptance policy lists the fields it needs: name and mailing address, date and time of collection, a daytime phone or email, the physical location and, for private wells, the source and whether chlorine was used to disinfect in the past two weeks. Add the faucet ("kitchen sink"), whether treatment was bypassed, and for lead, how long the water stood. When the report comes, compare received time with collection time, then use the report guide or the results checker. Not sure which tests belong in the kit? See the well water testing guide and which tests your well needs, then find a state-certified lab and ask for its sampling sheet first.

Questions people ask