PFAS Sampling Guidance

Page Index

Laboratories and Analytical Methods
Potential Sample Contamination
Minimizing Sample Contamination
Sampling Instructions
Sample Collection Video
For More Information

All community (C) public water systems and non-transient, non-community (NTNC) schools and daycares in Maine are required to sample finished drinking water for perfluoroalkyl and polyfluoroalkyl substances (PFAS). An interim standard of 20 ppt for six PFAS (alone or in combination) is in effect.

The six regulated PFAS are:

• perfluorooctanoic acid
• perfluorooctane sulfonic acid
• perfluorohexane sulfonic acid
• perfluorononanoic acid
• perfluoroheptanoic acid
• perfluorodecanoic acid

The DWP will continue to update this sampling guidance as new information becomes available.

 

Laboratories and Analytical Methods

Only DWP-accredited labs employing EPA methods 537 and 537.1 for use in potable water may be used. A reporting limit of 2 ng/L (nanograms per liter, a.k.a., parts per trillion or ppt) is required. Coordinate with the lab to deliver sample bottles to them in a timely manner so holding times will not be exceeded. Laboratories are responsible for submitting data to the DWP.

Maine-Accredited PFAS Laboratories (PDF)

For more information on labs and analytical methods, please contact Christine Blais:  Email or phone (207) 287-3220.

 

Potential Sample Contamination

Because PFAS can be found in many household, commercial and industrial items, care should be taken to prevent PFAS cross-contamination when collecting samples. Following the guidelines listed below (Minimizing Sample Contamination) will help reduce the potential for sample contamination, which would require additional sampling and analysis, possibly leading to unnecessary remedial actions. More information on the products listed here can be found in the Michigan Department of Environmental Quality’s General PFAS Sampling Guidance (PDF), revised 10/16/2018. No product endorsements are implied.

 

Minimizing Sample Contamination

A. Personal Hygiene and Personal Care Products
B. Food and Beverage
C. Clothing and Personal Protective Equipment (PPE)
D. Sample Bottles and Coolers
E. Sampling and Field Equipment
F. Field Documentation
G. Decontamination

 

A. Personal Hygiene and Personal Care Products

NO - Don't Use:

• Avoid use of cosmetics, moisturizers, hand cream, perfume, deodorant/antiperspirant, sunscreen, insect repellent or similar products that have not been determined to be PFAS-free on the day of the sampling event.

YES - Okay to Use:

The following insect repellents and sun-screens may be used on the day of sample collection, applied prior to arriving at the sample collection area. Other PFAS-free products may be acceptable.

Insect repellent:

• Deep Woods OFF

Sunscreen:

• Banana Boat Sport Performance Sunscreen Lotion Broad Spectrum SPF 30
• Neutrogena Ultra-Sheer Dry-Touch Sunscreen Broad Spectrum SPF 30

 

B. Food and Beverage

NO - Don't Use:

• No prepackaged food or fast-food packaging on the day of the sampling event.

• No food should be eaten in the staging or sampling areas.

YES - Okay to Use:

• Resealable plastic bags for food storage. Gatorade®, and Powerade® can be consumed outside the sampling area.

 

C. Clothing and Personal Protective Equipment (PPE)

NO - Don't Use:

• Clothing and other materials that have been laundered with fabric softeners, chemically treated to be waterproof, water repellent, stain resistant, insect resistant, and/or protective against ultraviolet rays, or anything that has been recently dry cleaned.

• Clothing or gear with Gore-Tex™, Carhartt, Tyvek®, or Teflon®.

YES - Okay to Use:

• Synthetic or cotton materials, polyurethane, polyvinylchloride (PVC), rubber, neoprene, powderless nitrile gloves.

• Clothing should be previously laundered (preferably previously washed greater than six times) without fabric softeners.

• Wet weather gear and boots made of polyurethane and PVC only.

 

D. Sample Bottles and Coolers

NO - Don't Use:

• Containers should not come in contact with carpeting or upholstery inside buildings or vehicles.

• Foil should not be used as a layer between stacked sample bottles.

• Do not use chemical (blue) ice packs to cool samples.

YES - Okay to Use:

• Sample bottles from the accredited laboratory.

• All sample containers must be polypropylene, and caps must be unlined polypropylene (no Teflon®-lined caps).

• Sample bottles should be stored in ZipLoc® bags and transported in coolers.

• Regular ice only in coolers.

 

E. Sampling and Field Equipment

NO - Don't Use:

• Latex or vinyl gloves.

• Pumps and tubing that contain Teflon® or other fluoropolymer-containing materials.

• Recycled or chemically treated paper towels.

YES - Okay to Use:

• New powderless nitrile gloves or gloves provided by the laboratory.

• High-density polyethylene (HDPE), bladders, silicone tubing, peristaltic pump or stainless-steel submersible pump.

• Untreated paper towels and cotton cloths.

 

F. Field Documentation

NO - Don't Use:

• Waterproof/treated paper or field book, plastic clipboard, spiral bound notebook, Sharpie® and permanent marker, Post-It® and other adhesive paper products.

YES - Okay to Use:

• Plain paper, metal clipboard, ballpoint pens, ZipLoc® resealable plastic storage bags.

 

G. Decontamination

NO - Don't Use:

• Decon 90

• Dawn dish detergent

YES - Okay to Use:

• Alconox® or Liquinox® or PFAS-free potable water followed by deionized rinse.

 

Sampling Instructions

Important: Read the instructions carefully.  The sampling procedure is complicated and has a high chance of producing false positives. If you have not fully reviewed the PFAS sampling guidance provided on this page, do so before beginning the sampling process. Additional guidance is available from Maine Rural Water Association (MRWA).

Before you begin:  As part of your pre-sampling planning, consider whether the water flowing through your sample port has contact with any Teflon® sealants, tapes, or tubing. If so, consider re-plumbing your sample port or using a different sample location. Wait at least 2 weeks between any plumbing activities and the sampling event.

Sampling Procedure

Sample your finished drinking water (point of entry to distribution system) using the following method. If the sampling instructions provided by the accredited lab conflict with these, please follow the instructions from the lab.

1. Fill out the sample analysis paperwork prior to arriving at the sampling location. Use a ballpoint pen. Avoid contact with any Teflon® tape or pipe thread paste on pipe fittings or sampling tap threads on the water supply discharge pipe. If the sampling port is constructed of Teflon® or low-density polyethylene (LDPE), a different sampling location should be used.
2. Run water for five minutes or until temperature has stabilized, whichever is longer. Then reduce the flow to avoid splashing when filling the sample bottle.
3. Wash your hands thoroughly. Use a new pair of nitrile gloves with each sample.
4. PFAS samples should be collected first, leaving field blank bottles (described below in Item 7) for later.
   Open the PFAS sample bottle. Do not put the cap on any surface and do not allow the inside of the cap, inside of the bottle, or bottle threads to be touched by any object.  Do not rinse the bottle as preservatives may be present.
5. Fill each sample bottle to the neck, or a fill line, if one is marked on the sample bottle. Use all bottles (except for field blank bottles).  Important: Only use sample bottles provided by the lab. Do not overfill (or allow preservative to escape).
6. Cap the bottle securely and gently flip the bottle upside down (approx. 5 times) until preservative is mixed in.  Do not re-open bottle from this point forward.
7. After collecting the PFAS sample, prepare a field blank at each sampling location. The purpose of the field blank is to identify potential PFAS contamination introduced during sample collection and handling. The lab will provide PFAS-free water for the field blank. Transfer this water into the field blank bottle at the sampling location, being careful to minimize contamination as described above. The lab will determine if the field blank(s) needs to be analyzed along with the rest of your samples.
8. Place each bottle in a sealed bag (ZipLoc® or other PFAS-free product), and place in a cooler that only contains PFAS samples (no other sample types) and ice. Your finished water sample(s) and field blank(s) should be in the same cooler. Do not use chemical (blue) ice packs.
9. Ensure the Chain of Custody (COC) form and all labels on bottles contain the required information, including sampling date and time.
   Important:  Be sure to sign the form. The sample will not be processed unless the form has a signature.
10. Samples must be chilled during shipment and must not exceed 10°C/50°F during the first 48 hours after collection.  Sample temperature must be confirmed to be at or below 10°C/50°F when the samples are received at the laboratory. Samples stored after 48 hours of collection must be held at or below 6°C/42°F. Samples should not be frozen. Adequate ice is particularly important when collecting samples during hot weather or for overnight sample shipment. Pre-chilling the samples in the refrigerator (keeping away from potential PFAS sources) prior to packing and shipping may be needed if the sample(s) will be shipped long distances.

If you have questions regarding the sampling process, contact your lab or call the DWP at (207) 287-2070.

View or download this information in a PDF.

 

Sample Collection Video

The Massachusetts Department of Environmental Protection Drinking Water Program has produced a video detailing how to collect raw water samples for PFAS analysis: Sample Collection for PFAS Testing at Public Water Supplies (YouTube).

 

For More Information

For general questions regarding PFAS and the new legislation, please contact the DWP PFAS Specialist:

• Courtany Hanley:  Email or phone (207) 592-2168

Updated 10/3/2024