How to Read a Water Quality Report

Every community water system in the United States publishes a Consumer Confidence Report, often called an annual water quality report. It is the best starting point for understanding the source of your municipal water, which regulated contaminants were detected, and whether the utility met federal and state drinking-water requirements.

It is also easy to misread.

A compliant report does not mean the water contains literally nothing. A detection does not automatically mean the water is unsafe. And a utility-wide report cannot tell you everything about the water at one kitchen sink.

Here is how to read the report as a homeowner rather than as a regulator.

Where to find your report

Community water systems must provide their report each year by July 1. Search the utility’s name plus “Consumer Confidence Report,” “CCR,” or “annual drinking water report.” EPA also provides a report-search tool. Starting in 2027, revised federal rules are intended to make reports easier to read and require systems serving more than 10,000 people to distribute them twice each year. (EPA; EPA CCR revisions)

Central Florida examples include:

Orlando Utilities Commission water-quality information
Orange County Utilities drinking-water reports
City and county utilities serving Kissimmee, St. Cloud, Clermont, Sanford, Lake Mary, and surrounding areas

Make sure the report belongs to the utility that serves the property. A mailing address can be in Orlando while the water provider is Orange County or another system.

Start with the source and treatment description

The first pages usually explain:

Whether the water comes from an aquifer, river, reservoir, or combination
How the utility treats and disinfects it
Whether chlorine or chloramine is used
How source-water protection is managed

This section gives context for the numbers later. A groundwater utility drawing from a limestone aquifer may have hard water even when every regulated contaminant is compliant.

Five terms used in the table

Term	What it means
MCL	Maximum Contaminant Level: the enforceable limit for a regulated contaminant
MCLG	Maximum Contaminant Level Goal: a non-enforceable health goal set without considering treatment cost or feasibility
Level detected	The result the utility reports, often an average
Range	The lowest and highest results during the reporting period
MRDL/MRDLG	Maximum Residual Disinfectant Level and its goal, used for disinfectants such as chlorine and chloramine

Do not compare two numbers until you confirm they use the same unit. Reports may use:

mg/L, or parts per million
µg/L, or parts per billion
ng/L, or parts per trillion

A thousand-fold conversion separates each of those units.

Detection is not the same as violation

Modern laboratories can identify chemicals at extremely low concentrations. A report may show a detected substance below its enforceable limit. That means the utility found and quantified it, not that the system violated the rule.

The useful questions are:

What was detected?
At what concentration?
What is the applicable limit or benchmark?
Was the result an average, a range, or a single sample?
Is the substance regulated, unregulated, or listed under a monitoring program?

Avoid two extremes: treating every detection as a crisis or treating every compliant result as irrelevant.

Read the range as well as the average

Some drinking-water requirements are evaluated using running annual averages or location-based averages. Averages are useful for understanding long-term exposure, but the reported range shows how results varied by time or sampling point.

A wider range can reflect season, treatment changes, water age in the distribution system, or different source wells. That does not automatically indicate a problem, but it is meaningful context, especially for disinfection by-products.

Pay attention to disinfectants and by-products

The report should identify whether the utility uses chlorine or chloramine and list the measured residual. EPA allows chlorine or chloramine up to 4 mg/L in drinking water, and CDC explains that the low residual helps control germs as water travels through the distribution system. (CDC)

The report may also list:

Total trihalomethanes, or TTHM
Haloacetic acids, or HAA5

These are disinfection by-products formed when disinfectants react with naturally occurring material in water. The federal limits are 80 parts per billion for TTHM and 60 parts per billion for HAA5. (EPA)

Disinfectant residual and by-products are related, but they are not the same measurement.

Look for hardness, but do not assume it will be listed

Hardness is usually a household-performance and aesthetic issue rather than a regulated health contaminant. Utilities are not always required to include it in the main compliance table.

When listed, hardness may be reported in mg/L or ppm as calcium carbonate. Divide by 17.1 to convert to grains per gallon.

OUC, for example, currently publishes an average hardness of 129 ppm, or about 7 grains per gallon. A utility average is useful for context, while an at-the-tap test is better for equipment settings and sizing. (OUC)

Understand what a utility report cannot tell you

It is not a test of your individual faucet

The utility samples the source, treatment system, and distribution network according to regulatory protocols. Once water enters private plumbing, the home’s service line, solder, fixtures, water heater, and periods of stagnation can affect conditions at the tap.

Lead is a familiar example: the source may be household or service-line materials rather than the water leaving the treatment plant.

It does not list every chemical that can be measured

The report focuses on regulated contaminants and required monitoring. Utilities may publish PFAS or other unregulated-contaminant results separately.

It may not answer a taste, odor, scale, or appliance question

A utility can meet all health standards while the homeowner still notices hardness, chlorine taste, or scale. Those are legitimate treatment preferences, but they should not be confused with a regulatory violation.

A five-minute way to review the report

When you open the report, find:

Your water source
The disinfectant used
Hardness, if published
TTHM and HAA5 results
Lead and copper information
PFAS or unregulated monitoring links
Any violation or public notice
The utility contact number

Then compare the report with what you observe at home:

Is the concern scale or spotting?
Is it taste or odor?
Is it drinking-water preference?
Is it a specific contaminant with a published result?
Could the home’s plumbing be part of the question?

That step prevents buying a system intended for a different problem.

Frequently asked questions

Does a compliant water report mean I do not need treatment?

It means the utility met the applicable drinking-water requirements for the reported period. A homeowner may still choose treatment for hardness, taste, odor, drinking-water preference, or a specific certified reduction goal.

Why does the report show a contaminant if the utility is compliant?

A laboratory detection can be below the enforceable limit. “Detected” and “in violation” are different statements.

Why is hardness missing from my report?

Hardness is not generally regulated as a health contaminant, so it may appear in a utility FAQ or technical data sheet rather than the required compliance table.

Should I test my own tap?

Use the utility report first. At-home screening can be useful for hardness and disinfectant residual. Specific contaminants such as PFAS, lead, bacteria, or arsenic require the correct certified laboratory method and sampling protocol.

How to Read Your Water Quality Report Without Getting Lost in the Table