How to Read Your Water Quality Report

Where do you find your water quality report?

Your supplier posts it online and must send it out each year by July 1. The State Water Board's CCR page says the 2025 report covers January 1 through December 31, 2025 and was due to customers by July 1, 2026. EPA also runs a search tool for finding any system's report.

In the Valley, the four current reports are LADWP's Drinking Water Quality Report 2025 (published July 2026), Burbank Water and Power's report on its water quality reports page (printed in its June 2026 newsletter), Glendale Water & Power's report on its reports page (published July 1, 2026), and the City of San Fernando's annual report. Your water bill names your supplier if you are unsure, and the tap water folder maps who serves which neighborhood.

What do MCL, PHG and DLR mean?

The MCL is the legal ceiling, the PHG is the health goal, and the DLR is the lowest level a lab must report. LADWP's report defines each on page 20. An MCL (maximum contaminant level) is "the highest level of a contaminant that is allowed in drinking water", set as close to the PHG as is technically and economically feasible.

A PHG (public health goal) is the level below which there is no known or expected risk, set by California's environmental protection agency. EPA's version is the MCLG. Chromium-6 shows how far apart the two can be: the State Water Board's FAQ gives an MCL of 10 µg/L, a PHG of 0.02 µg/L and a DLR of 0.1 µg/L. A result above the PHG but below the MCL is legal; the chromium-6 page puts the Valley's 2025 figures against both.

A few other letters turn up. AL is the action level, used for lead and copper at household taps. MRDL is the disinfectant limit, 4 mg/L for chloramine. NL, a notification level, is an advisory figure for chemicals that have no MCL yet. TT means a treatment technique is required instead of a number.

Which table applies to your neighborhood?

It depends on your supplier, and on LADWP water it also depends on where in the city you live. LADWP's page 21 sends San Fernando Valley readers to three plant columns: MWD Jensen, the Northern Combined Wells, and the Los Angeles Aqueduct Filtration Plant in Sylmar. Western LA reads only the aqueduct plant, and the Harbor area reads the three MWD plants. A few results, such as the disinfectant and lead, are reported city-wide.

Burbank prints one column, "Burbank Water", covering imported supply mixed with groundwater that Burbank treats itself. Glendale prints three: MWD Weymouth water, MWD Jensen water and its own Glendale Water Treatment Plant, and some plant figures were measured before blending. San Fernando prints one column for its well system.

LADWP sorts its results into four tables: health-based primary standards, aesthetic secondary standards, unregulated substances, and a federal survey of emerging contaminants sampled in 2023 and 2024. The water sources page explains why the Valley gets three columns.

What do ppm, ppb and ppt mean?

They are parts per million, billion and trillion, and each matches a metric unit: ppm is mg/L, ppb is µg/L and ppt is ng/L, as Burbank's 2025 report spells out in its abbreviations. One ppm equals 1,000 ppb, and one ppb equals 1,000 ppt.

The unit changes by substance, so read it before the number. Hardness and nitrate come in mg/L, chromium-6 and lead in ppb, and PFAS in ppt: EPA's limit for PFOA is 4.0 ppt. To turn hardness into grains per gallon, divide mg/L by 17.1, as Glendale's footnote says; Burbank's 286 mg/L becomes about 16.7 gpg. The hardness page has every supplier's figure.

Watch for averages that look larger than their range. LADWP marks some results "HRAA", the highest running annual average, which can include samples from the year before and so sit above that year's range. Most limits are judged on yearly averages, not single samples.

What do secondary standards cover?

Secondary standards (SMCLs) cover taste, odor and appearance, not health. LADWP's secondary table lists chloride (500 mg/L), iron (300 µg/L), manganese (50 µg/L) and total dissolved solids (1,000 mg/L), among others. Its Valley sources ran 234 to 297 mg/L in TDS in 2025, well under that level.

The figures printed can differ between reports: San Fernando's table shows 500 mg/L for TDS, the lower of California's two secondary levels. Odor is scored in threshold odor numbers; Burbank reported 0.0 against a limit of 3.

Hardness is not in either standards table, because it has no limit. LADWP lists it among unregulated substances, at 103 mg/L for aqueduct plant water, 115 for the Northern Combined Wells and 140 for Jensen water in 2025. That is a comfort and scale question, which the softener page takes up.

What should you look for first in a water quality report?

Look at the compliance column, then lead, then any notices. LADWP's tables carry a "Meets Primary Standard" column of YES or NO, and San Fernando's has a violation column. A NO in the first, or a Yes in the second, is the line to read in full.

Next, find the lead and copper table: it gives a 90th-percentile result from home taps, the number of homes sampled and how many were over the action level. LADWP's 2023 round shows 3.9 ppb, with 3 of 105 homes over 15 ppb. The lead page explains why that figure reflects home plumbing.

Then read the text pages. LADWP's 2025 report prints an arsenic advisory because its highest result, 7.0 µg/L, passed 5 µg/L, half the limit, and it describes chlorate found in two storage tanks. If you are buying treatment, note your disinfectant and hardness too; the chloramine page covers the first.

Finally, sanity-check odd figures against the state's. San Fernando's 2025 table prints the chromium-6 PHG as 20, where the state's goal is 0.02 µg/L, and lists a chlorine average of 2.07 ppm that falls outside its own printed range of 1.45 to 1.89. The State Water Board's Drinking Water Watch database holds the underlying sample data.