LCRI Water Quality Parameter and Corrosion Control Monitoring: What Utilities Must Track by 2027

Introduction: Monitoring Beyond the Tap

This is the companion article to LCRI Tap Water Monitoring Requirements: Site Sample Plans, Tier Priorities, and What to Expect by 2027. That article covered tap water sampling, site sample plans, and the five-tier priority system. This one covers the second major monitoring category under the LCRI: water quality parameter (WQP) monitoring, which includes both distribution system sampling and entry point monitoring tied to corrosion control.

The Final LCRI was published in the Federal Register on October 30, 2024 (89 FR 86418) and became effective December 30, 2024. It is codified at 40 CFR Part 141 Subpart I.

Water quality parameter monitoring requirements may be less familiar than tap sampling to many compliance staff, but they carry significant consequences for systems that fail to maintain optimal corrosion control treatment. Here is what you need to know.

What Are Water Quality Parameters and Why Do They Matter?

Water quality parameters (WQPs) are chemical measurements, such as pH, alkalinity, and inhibitor concentrations, that the State designates based on corrosion control studies and lead and copper sampling results. They are the benchmarks used to determine whether a water system’s corrosion control treatment is operating optimally.

WQPs in effect on the compliance date were established under previous Lead and Copper rules and remain in effect unless the system fails to meet lead and copper action levels and water quality parameter ranges, or makes source water or treatment changes. WQP revisions after the compliance date will be based on corrosion control studies and lead and copper monitoring results conducted pursuant to the LCRI.

Distribution System Monitoring Requirements

Water quality parameter monitoring must be conducted in the distribution system and at entry points to the distribution system.

Where Distribution System Samples Are Collected

Distribution system sampling can occur at tap sampling sites or at sites used for total coliform sampling (see 40 CFR 141.21) and must be included in the Site Sample Plan. The following parameters must be measured in the distribution system:

pH
Alkalinity
Orthophosphate, if an orthophosphate-containing inhibitor is used
Silica, if a silica-containing inhibitor is used
Any other parameters designated by the State

Standard Number of Distribution System Sampling Sites

Water Quality Parameter Monitoring Table (Standard Sites Required):

More than 100,000 people served: 25 sites
10,001 to 100,000: 10 sites
3,301 to 10,000: 3 sites
501 to 3,300: 2 sites
101 to 500: 1 site
Fewer than 100: 1 site

Reduced Distribution System Monitoring

A water system that meets lead and copper action levels and required water quality parameters may reduce the number of locations to be sampled:

Reduced Water Quality Parameter Monitoring Table:

More than 100,000: 10 sites
10,001 to 100,000: 7 sites
3,301 to 10,000: 3 sites
501 to 3,300: 2 sites
101 to 500: 1 site
Fewer than 100: 1 site

Other requirements may apply depending on the optimal corrosion control treatment (OCCT) designated by the State.

Entry Point Monitoring Requirements

Entry points to the distribution system include all sources that contribute flow to the system after treatment. Entry point sampling is separate from distribution system sampling and carries its own requirements.

What Must Be Sampled at Entry Points

pH
When alkalinity is used as a corrosion control measure: a reading of the dosage rate and alkalinity concentration
When a corrosion inhibitor is used for corrosion control: a reading of the dosage rate and concentration
Any additional parameters specified by the State

Frequency of Entry Point Sampling

The number of entry point samples required depends on whether the system has installed or re-optimized optimal corrosion control treatment and whether State-designated optimal water quality parameters are in place.

For systems WITHOUT installed or re-optimized OCCT AND without State-designated OWQPs: Two samples at each entry point during each monitoring period.
For systems WITH installed or re-optimized OCCT AND/OR State-designated OWQPs: One sample from each entry point every two weeks during each monitoring period.

Schools and Child Care Facility Monitoring

Monitoring for lead in schools and child care facilities must also begin by November 1, 2027. The requirements for school and child care facility monitoring are discussed in the previous LCRI article at 40 CFR 141.92 on the SAMS website.

What You Get with SAMS LCRI

We Already Did the Hard Part!

SAMS Water LCRI Module delivers a turnkey approach to Lead and Copper Rule compliance, managing facility identification, required letters, sampling coordination, and regulatory tracking. Already a SAMS client? Add it seamlessly to your existing compliance system.

Putting It Together: What Systems Should Be Tracking Now

Water quality parameter monitoring is not a stand-alone obligation. It sits inside a web of corrosion control treatment requirements, tap sampling results, and State designations. A system that loses track of its OCCT status, its OWQP range, or its distribution system sampling obligations can find itself out of compliance on multiple fronts simultaneously.

Utilities that use compliance management software to track WQP monitoring schedules, document entry point readings, and maintain corrosion control treatment records are far better positioned to catch drift before it becomes a violation. SAMS by NJBSoft supports these workflows across drinking water compliance programs.

A Note on Preparation

The LCRI is a technically detailed rule. The tap monitoring requirements covered in the companion article, and the water quality parameter monitoring requirements covered here, together represent a significant compliance obligation. As always: the devil is in the details. If you are responsible for drinking water rule compliance at your utility, please review the LCRI directly and work closely with your State primacy agency to confirm your obligations.

CFR Reference: 40 CFR Part 141 Subpart I

Federal Register: 89 FR 86418, October 30, 2024

eCFR Link: eCFR Link: https://www.ecfr.gov/current/title-40/chapter-I/subchapter-D/part-141