Which Sample Tubing Should I Use?

March 10, 2026

A practical guide to selecting the right tubing for groundwater sampling including LDPE, HDPE, Silicone, FEP, and PTFE, and knowing when each type is appropriate.

 

When your job calls for sampling groundwater using a pump, one of the most important and sometimes overlooked decisions is which tubing to use. The wrong choice can compromise your sample integrity, skew analytical results, and potentially invalidate your entire sampling event. 

 

Tubing isn’t just a conduit. Depending on its material, it can absorb contaminants, leach plasticizers, or interact chemically with the compounds you’re trying to detect. For analytes like PFAS, VOCs, and other trace-level contaminants, the tubing you run your sample through matters as much as the pump you use or the bottles you fill. 

 

Below, we break down the most common types of sample tubing used in environmental groundwater programs, their key characteristics, and the applications they’re best and worst suited for. Always check with local, state, and federal regulations for your specific site requirements.

 

  1. The Most Common Types of Sample Tubing 

Sample tubing for groundwater programs generally falls into four material categories: LDPE, HDPE, Silicone, and FEP/PTFE (Teflon®) Lined LDPE. Each has a distinct chemical profile, flexibility, cost point, and set of recommended applications. 

 

LDPE — Low Density Polyethylene 

LDPE tubing is one of the most widely used materials in environmental groundwater sampling, and for good reason: it is inexpensive, readily available, and reasonably flexible, making it easy to deploy and retrieve across a wide range of well depths. 

 

Pros:

  • Cost-effective and widely available
  • Flexible enough for most well configurations
  • Suitable for a broad range of standard groundwater analytes 
  • Some manufacturers certify their LDPE tubing as PFAS-free after appropriate testing

 

Cons:

  • Flexibility can be a drawback at greater depths, the tubing may stretch under its own weight 
  • Not recommended for PFAS sampling due to potential absorption and subsequent leaching 
  • Concerns stem from the extrusion process, which may introduce PFAS-related compounds

 

PFAS Note: Standard LDPE tubing is not recommended for PFAS sampling. However, some manufacturers have performed the necessary testing to certify their LDPE tubing as PFAS-free. If LDPE is required on a PFAS site, verify that the specific product carries this certification.

 

HDPE — High Density Polyethylene 

HDPE tubing offers greater chemical resistance than its low-density counterpart, making it the preferred choice for more chemically demanding sampling environments, most notably PFAS investigations. 

 

The tradeoff is flexibility. HDPE is stiffer than LDPE, which can make it somewhat less convenient to work with, particularly in shallow wells or applications that require the tubing to navigate tight bends. That said, for PFAS sampling programs, HDPE is the industry-recommended tubing material and should be the default choice wherever PFAS contamination is a concern. 

 

  • Best for: PFAS sampling, sites with aggressive chemical matrices 
  • Limitation: Less flexible than LDPE; may be harder to handle in certain well configurations 
  • Chemical resistance: Higher than LDPE across most compound classes 

 

Silicone Tubing 

Silicone tubing has a specific and well-defined role in groundwater sampling programs: it is used primarily in the pump head of peristaltic pumps. Its softness and elasticity make it ideal for the repeated compression and release that drives fluid through a peristaltic pump mechanism.

 

However, silicone is not recommended as the primary sample line tubing for groundwater sampling. Its high gas permeability means that volatile compounds can diffuse through the tubing wall, compromising sample integrity particularly for VOC analyses. Keep silicone in the pump head where it belongs, and route the actual sample through a more appropriate tubing material. 

 

  • Appropriate use: Pump head tubing for peristaltic pumps
  • Not appropriate for: Primary sample line, especially VOC or PFAS sampling 
  • Key limitation: High permeability allows gases and vapors to pass through the tubing wall 

 

FEP / PTFE — Teflon® Lined LDPE Tubing 

FEP (Fluorinated Ethylene Propylene) and PTFE (Polytetrafluoroethylene), commonly known by the brand name Teflon®, are among the most chemically inert materials available for sample tubing. They resist virtually all solvents, acids, and bases, and do not absorb or leach contaminants under normal conditions. 

 

Despite this impressive chemical profile, FEP/PTFE tubing is not recommended for PFAS sampling. This may seem counterintuitive given its inertness, but PTFE and FEP are themselves fluoropolymers, a class of compounds within the broader PFAS family. Their use introduces potential contamination concerns in PFAS-sensitive programs. 

 

Due to its relatively high cost, FEP/PTFE is most commonly used as an inner lining for LDPE tubing in VOC sampling applications, where its chemical inertness protects the sample from interaction with the outer LDPE layer. 

 

  • Best for: VOC sampling as a liner inside LDPE tubing 
  • Not recommended for: PFAS sampling (fluoropolymer material)
  • Cost: Higher than LDPE and HDPE; typically used strategically, not as primary tubing

 

  1. Quick Reference: Tubing Selection by Application 

Not sure which tubing to reach for? Here’s a plain-language summary: 

 

General groundwater sampling (non-PFAS, non-VOC): LDPE is a cost-effective and widely accepted choice. 

 

PFAS sampling: Use HDPE. It is the industry-recommended material for PFAS programs. Avoid standard LDPE, FEP, and PTFE.

 

VOC sampling: Consider LDPE with an FEP/PTFE inner liner to minimize compound interaction with the tubing wall. 

 

Peristaltic pump head: Use silicone tubing in the pump head, but switch to an appropriate primary line material (LDPE, HDPE) for the sample tubing. 

 

Chemically aggressive matrices: HDPE offers the best chemical resistance among common polyethylene options.

 

  1. Sizes, Lengths, and Bonded Dual Tubing 

All of the tubing types described above are available in multiple inner diameters and lengths to suit a wide range of pump configurations and well depths. Selecting the correct inner diameter is important for maintaining proper flow rates and minimizing purge volumes. 

 

For applications using bladder pumps or double valve pumps, which require two separate lines running down the well simultaneously, bonded dual tubing is available. This product bonds two tubes side by side into a single flat ribbon, keeping the airline and sample line together for cleaner, easier deployment and retrieval. It reduces tangling, simplifies well entry, and helps maintain consistent pump depth across sampling events. 

 

  • Available in LDPE and Teflon® Lined LDPE materials
  • One line serves as the airline (pressure/gas line); the other carries the groundwater sample
  • Simplifies deployment in two-line pump applications
  • Available in standard sizes to match most bladder and double valve pump configurations

 

  1. Always Check Your Regulatory Requirements 

Tubing selection is not purely a technical decision, it is often a regulatory one. Many state environmental agencies specify acceptable tubing materials in their groundwater sampling guidance documents, and federal programs such as CERCLA and RCRA may impose additional requirements. Requirements can also vary by analyte class. 

 

Before selecting tubing for any sampling event, review the applicable site-specific sampling and analysis plan (SAP), quality assurance project plan (QAPP), and any state or federal guidance that governs your site. When in doubt, consult with your project manager or regulatory contact before mobilizing.

 

Reminder: Always check with local, state, and federal regulations for your specific site. The guidance in this post is general in nature and does not substitute for site-specific regulatory requirements.

 

Find the Right Tubing for Your Next Sampling Event 

Environmental Equipment + Supply stocks LDPE, HDPE, FEP/PTFE-lined, and bonded dual tubing in a range of sizes and lengths. Whether you’re outfitting a routine monitoring program or a large-scale PFAS investigation, we can help you select the right product for your application. 

 

Contact us at [email protected] or visit www.envisupply.com to browse our tubing inventory.

Posted in Environmental monitoring