Is My Water Safe? How to Read Your Water Quality Report

What Is a Consumer Confidence Report?

Every community water system serving residential customers is required by the Safe Drinking Water Act to send an annual Consumer Confidence Report (CCR) to all customers by July 1. This document, also called the Annual Water Quality Report, lists every regulated contaminant that was detected in your water that year.

The CCR includes:

• The name and source of your water (groundwater, surface water, or purchased)
• Each detected contaminant and its concentration
• The Maximum Contaminant Level (MCL) - the legal limit for each contaminant
• The MCL Goal (MCLG) - the health-based target, often lower than the enforceable MCL
• Whether any violations occurred and what was done about them
• Contact information for your water utility

If you have not received a CCR, search your utility's website or contact them directly. Renters should ask their landlord or property manager for a copy. You can also search for your water system on PlainWater's systems directory to see violation and compliance data from EPA.

Understanding Maximum Contaminant Levels (MCLs)

MCLs are the backbone of drinking water regulation. Each regulated contaminant has an enforceable MCL set by EPA. These are not zero-risk thresholds, they represent the lowest level that water systems can feasibly achieve using available treatment technology, balancing health protection with cost and technical capability.

Key concepts:

When reading your CCR, a contaminant detected at 80% of its MCL is technically compliant but worth monitoring. A detection at 5% of the MCL is well within normal range. The closer to the limit, the more attention it warrants, especially for contaminants with MCLGs of zero (carcinogens).

How to Read Your CCR: A Step-by-Step Approach

Here is how to extract the most useful information from your annual water quality report:

1. Check for violations first. The CCR must disclose any violations and explain what was done. Any health-based violation is a significant finding. If there were none, your system met all regulatory requirements that year.
2. Look at the contaminant table. Scan the "Detected Level" or "Range" column. Focus on contaminants where the detected level is more than 50% of the MCL, these are within compliance but closer to the edge.
3. Check for lead and copper. These are measured at the tap (not at the treatment plant) through periodic sampling of homes with lead service lines or lead solder. The "action level" for lead is 15 ppb at the 90th percentile, meaning 90% of sampled homes must be below this. If your home was built before 1986, lead in your plumbing is possible even if the system passes.
4. Note disinfection byproducts. Trihalomethanes (TTHMs) and haloacetic acids (HAA5) form when chlorine reacts with organic matter in water. These are common detections and are regulated at 80 ppb and 60 ppb respectively. Levels near the MCL are common in systems using surface water, not a crisis, but worth monitoring if you are sensitive to this risk.
5. Check the source water assessment. The CCR should describe your water source (groundwater or surface water) and its susceptibility to contamination. Groundwater is generally less susceptible to microbial contamination but more susceptible to certain chemical contaminants that persist in aquifers.

Decoding Sample Detections in Plain Numbers

When the detected level is well under the MCL

A detection at less than 25% of the MCL is generally background-level and well within the safety margin most regulators target. For example, an arsenic reading of $0.002 mg/L against an MCL of $0.010 mg/L is roughly 20% of the limit, a typical reading for groundwater in regions with no industrial source.

When the detected level approaches the MCL

A detected level above 75% of the MCL warrants closer reading of the trend. A nitrate reading at $7.5 mg/L against the $10 mg/L MCL is 75% of the limit, compliant today but worth tracking against the prior two reports. If the trend is upward (e.g. last year was $5.0 mg/L, two years ago was $3.0 mg/L) you may want to ask your utility about source-water protection plans.

When the detected level exceeds the MCL

An exceedance triggers a formal violation. The CCR must disclose what action was taken and the timeline for return to compliance. Suppose total trihalomethanes (TTHM) measured $90 µg/L against the $80 µg/L MCL, that is 12.5% above the limit. The system would issue a Tier 2 public notice, increase monitoring, and adjust disinfection practices, with results typically visible within a quarter.

When the detection is for an unregulated contaminant

Some CCRs disclose results for unregulated contaminants, typically PFAS, 1,4-dioxane, or chromium-6, where EPA has not yet set an MCL but is collecting data under UCMR. These detections do not trigger violations, but they signal what regulators may target next. PlainWater's PFAS tracker shows UCMR5 results by system.

"An MCL is not a safety guarantee, it's the lowest concentration regulators believe most systems can reliably achieve. The MCL Goal (MCLG) is the actual health-protective target, and is sometimes zero."

What Your CCR Does Not Tell You

The CCR has important blind spots:

• Building plumbing. The CCR reflects water quality at the treatment plant or in the distribution system. It does not measure what comes out of your specific tap. Old pipes, lead solder, or galvanized steel in your building can add contaminants between the main and your faucet.
• Unregulated contaminants. The CCR covers regulated contaminants (those with enforceable MCLs). Emerging contaminants that EPA has not yet regulated may be present but not listed. PFAS is the most notable example, only six PFAS compounds received MCLs in 2024.
• Private wells. If your water comes from a private well, there is no CCR. You are responsible for your own testing. EPA recommends annual testing for bacteria and nitrates, and periodic testing for other contaminants based on local conditions.
• Real-time conditions. The CCR is an annual snapshot. Water quality can change during the year due to seasonal variation, infrastructure events, or contamination incidents. Boil-water advisories and do-not-drink orders are issued separately and supersede CCR data.

Using PlainWater to Supplement Your CCR

PlainWater provides data from EPA's Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. Use it to:

1. Check your system's full violation history - not just the current year. Systems with patterns of violations across multiple years face systemic issues. Search by county or state.
2. Check for PFAS detections. The UCMR5 program tested most large water systems for 29 PFAS compounds. Your CCR may not include these results. PlainWater does.
3. Compare your system against regional and national baselines. County-level pages show average violation rates and PFAS detection rates, letting you see how your system compares.
4. Check the status of violations. PlainWater shows whether violations are resolved or ongoing, critical context that CCRs sometimes omit.

When to Consider Action

Most tap water in the United States meets federal standards. However, consider taking additional steps if:

• Your system has ongoing health-based violations - contact your utility for the timeline and install appropriate filtration
• PFAS detections are above 4 ppt for PFOA or PFOS, a reverse osmosis filter certified to NSF Standard 58 is the most effective household treatment
• Your home was built before 1986 - run cold water for 30 seconds before drinking (flushes standing water from pipes), and consider having your tap water tested for lead
• You have infants, pregnant women, or immunocompromised household members, these groups are more vulnerable to contaminant levels that are technically compliant
• You are on a private well - test annually and after any flooding or nearby construction

Frequently Asked Questions