Tips for Taps Blog

What is 5th liter sampling?

LCRR: Improving Lead Sampling Through the 5th Liter Requirement


The chief priority of the Environmental Protection Agency’s (EPA) Lead and Copper Rule Revisions (LCRR) is getting the lead out of the nation’s drinking water. 

This requires a rigorous water testing program to better understand and locate lead contamination. Robust sampling methods are essential to determining whether the source of potential lead contamination is a service line or leaded plumbing materials within a residence. 

To account for this, the new revisions include changes to sampling protocols. In this guide, we’ll be focusing on a specific sampling feature of the LCRR: the 5th liter requirement.

Our LCRR coverage includes:

The Importance of Lead Sampling

If lead is found in drinking water, it is crucial to identify where it is coming from within the water system. To do this, samples must be taken at every stage—from the treatment plant to the tap in households that are part of a lead sampling campaign. However, how you sample lead at the tap can help you determine if the lead is coming from your faucet/fixtures and on-premise pipes or if the lead comes from the distribution system pipes.

Originally, the EPA’s Lead and Copper Rule (1991) required test sampling to be taken from the first liter of water, or “first draw,” whether the material in question was copper or lead. This approach does not clearly indicate whether lead contamination may happen in the distribution system. 

A smaller sample volume with no prior flushing (“first draw”) provides information about water quality that has traveled a short distance in the home’s plumbing system, while a larger volume sample (e.g. the 5th liter) more clearly provides information about water that has traveled a longer distance from the distribution system.

As a result, under the original LCR, lead samples do not clearly separate whether lead at the tap is the result of on-premise plumbing or the distribution line pipes. Under the new revisions, all lead-identified, lead-lined galvanized—known as “galvanized requiring replacement,” and pipes with “lead status unknown” will require testing using the 5th Liter sampling protocol. 

Note: Your utility will be required to notify you annually if a lead, galvanized or unknown service line is a part of their inventory until the line is removed or verified.

Collecting a Water Sample—SimpleLab Tap Score 

What Is 5th Liter Sampling?

The EPA’s 5th liter sampling rule targets water that flows from the lead service lines, not just the faucet or the premise plumbing, so tests can identify problems sooner. 

For homes with or suspected of having LSLs, the compliance sample must come from the 5th liter of water drawn at the tap.

  • If your home is selected for testing, you will collect five (5) one-liter samples, consecutively numbered, from the kitchen or bathroom faucet.
  • Sampling at this volume captures water that has come in contact with the LSL during an instructed stagnation period (a specified period of time at which no water should flow from any fixtures). (The EPA now recommends against pre-stagnation flushing, i.e. flushing your tap for a specific period of time prior to starting the stagnation period. Flushing potentially lowers lead levels.) Analysis will then come from the first liter bottle for copper, and the fifth liter bottle for lead. 
  • For all service lines other than LSLs, sampling will continue as a first draw, one-liter sample taken from the kitchen or bathroom faucet. 

Why the 5th Liter?

The water that reaches your home comes from a long network of pipes. Water’s approach to your faucet can be divided into three lines: 

  1. Your premise plumbing (first 3 liters)
  2. The service line (approx. liters 4-8)
  3. The water main (after the 8th liter)

Typically, the first three liters of water that leave your faucet come from water still in the plumbing of your home or building, or the premise plumbing.

Approximately liters four through eight are pulled from the service lines, or the pipes that connect your premises to the water main. Traditionally, these lines were made of lead and are now a major issue standing in the way of clean drinking water.

After the eighth consecutive liter, water flowing through your pipes is coming from the water main, or the primary underground pipe in a municipal water distribution system. 

Questions About Lead Sampling?

It’s important to collect samples at various volumes in order to properly identify the potential sources of lead within a home or building, but more crucially, along the distribution route. By targeting the service line, 5th liter sampling should play a major role in the LCRR’s fight against lead contamination. If you have any questions related to sampling procedures, the Lead and Copper Rule Revisions, or anything else, let us know! Our experts are always on call and available to help answer any of your water testing needs. 

author portrait
About The Author


Sasha Sosnowski is a writer and editor from Los Angeles, California. He studied journalism and history at the University of Warsaw and the University of Arts London and has demonstrated his skills through professional roles as a research assistant, proofreader, magazine editor, and essayist. In his spare time, Sasha enjoys working on his collection of vintage typewriters.
back to top