1Your water
2Your home
3Your system

Your local water, explained

San Diego water quality report

Very hard City plant water makes scale control worth planning alongside chloramine filtration.

The three City plant averages are very hard; purchased treated water differs. Use the provider-specific results below before matching treatment to your home.

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Your water

Match the name on your water bill.

Check the supplier on your water bill. City and county boundaries can include several water systems.

Water provider / system

Only the listed water system is summarized here. Choose “Other / not sure” if your bill shows a different supplier.

This is the provider and system on my water bill.

These are utility measurements, not a test at your tap or a current service advisory. Sources checked October 25, 2026

Showing utility report

City of San Diego Public Utilities Department

2025 utility report; each result retains its sampling year

Only use these results if City of San Diego Public Utilities Department is the supplier on your bill. Other utilities and private wells need their own data.

Your water at a glance

See the amount, the comparison and what it means. “Below” refers to the stated benchmark, not zero risk.

Hardness

Very hard at City plants

237–243mg/L as CaCO₃

Range of three City plant averages

USGS: very hard >180 mg/L

Purchased treated water averages 145 mg/L (hard) and has a wider range. See each supply below.

2025

View source ↗

Disinfectant residual

Below 4 mg/L MRDL

1.75mg/L

Chloramines · distribution average

Range: ND–3.80 mg/L. Choose filtration with verified chloramine performance.

2025

View source ↗

TTHM

Below 80 ppb MCL

55ppb

Maximum locational running annual average

Individual samples are not the annual-average compliance result.

2025

View source ↗

HAA5

Below 60 ppb MCL

15ppb

Maximum locational running annual average

Individual samples are not the annual-average compliance result.

2025

View source ↗

Fluoride

Below California 2 mg/L MCL

0.6–0.8mg/L

Range of final-water plant averages

Full final-water range: 0.2–0.9 mg/L. Natural and final-water fluoride rows are not added together.

2025

View source ↗

Lead

Below 15 ppb action level

ND (<5)ppb

90th percentile · 56 sampled taps

0 of 56 sites exceeded the action level. Your plumbing can affect your tap.

2023

View source ↗

Arsenic

Below reporting limit

ND (<2)ppb

Supplementary nondetect list

Not detected is not zero; MCL 10 ppb differs from the 0.004 ppb health goal.

2025

View source ↗

PFAS — PFBA

Detected; no MCL listed

5.4ppt

Alvarado average · range ND–7.0

Other plant averages were ND. Do not compare PFBA to PFOA/PFOS limits.

2025

View source ↗

Your filtration starting point

Filtration + softening make sense here.

We recommend filtration matched to chloramine plus a softener for mineral scale. The three City plant averages are very hard; the purchased treated-water average is hard. Confirm your home’s current hardness and flow for final sizing.

Choose filtration for your disinfectant, taste, odor and sediment goals.
Reduce hardness minerals that leave scale and spots.

Find My Water System →

Your water → your home → your system

You buy the equipment. You hire and pay your own licensed plumber.

View equipment details

Filtration and softening serve different goals. Check the exact model’s reduction claims; standard filtration is not a promise to remove every substance in this report.

View Full Water ReportOpen the measured results, dates, comparisons and original utility report.

The numbers behind your report

Selected results with the original sampling dates and measurement basis. Open the utility report for every parameter, notice and footnote.

Open the complete utility report ↗

Find a result

What was measured	Reported amount	Sample year / source date	How to read it
Hardness	237–243 mg/L as CaCO₃Range of three City plant averages	2025View source ↗	Very hard at City plantsPurchased treated water averages 145 mg/L (hard) and has a wider range. See each supply below.
Disinfectant residual	1.75 mg/LChloramines · distribution average	2025View source ↗	Below 4 mg/L MRDLRange: ND–3.80 mg/L. Choose filtration with verified chloramine performance.
TTHM	55 ppbMaximum locational running annual average	2025View source ↗	Below 80 ppb MCLIndividual samples are not the annual-average compliance result.
HAA5	15 ppbMaximum locational running annual average	2025View source ↗	Below 60 ppb MCLIndividual samples are not the annual-average compliance result.
Fluoride	0.6–0.8 mg/LRange of final-water plant averages	2025View source ↗	Below California 2 mg/L MCLFull final-water range: 0.2–0.9 mg/L. Natural and final-water fluoride rows are not added together.
Lead	ND (<5) ppb90th percentile · 56 sampled taps	2023View source ↗	Below 15 ppb action level0 of 56 sites exceeded the action level. Your plumbing can affect your tap.
Arsenic	ND (<2) ppbSupplementary nondetect list	2025View source ↗	Below reporting limitNot detected is not zero; MCL 10 ppb differs from the 0.004 ppb health goal.
PFAS — PFBA	5.4 pptAlvarado average · range ND–7.0	2025View source ↗	Detected; no MCL listedOther plant averages were ND. Do not compare PFBA to PFOA/PFOS limits.
Nitrate as nitrogen	ND mg/L as NAll plant averages · largest sample 0.5	2025View source ↗	Below 10 mg/L MCLND is below the reporting limit.
PFOA and PFOS	ND (<2) pptSupplementary nondetect list	2025View source ↗	Below reporting limitsDoes not erase the separate PFBA detection.
Hardness — Alvarado	237 mg/L as CaCO₃Average · range 203–270	2025View source ↗	very hardCalculated average: 13.8 gpg.
Hardness — Miramar	242 mg/L as CaCO₃Average · range 200–285	2025View source ↗	very hardCalculated average: 14.1 gpg.
Hardness — Otay	243 mg/L as CaCO₃Average · range 201–271	2025View source ↗	very hardCalculated average: 14.2 gpg.
Hardness — Purchased treated water	145 mg/L as CaCO₃Average · range 54.4–232	2025View source ↗	hard average; range spans soft through very hardCalculated average: 8.5 gpg.
TDS — Alvarado	532 mg/LAverage · range 434–590	2025View source ↗	Below 1,000 mg/L secondary MCLAesthetic benchmark; this does not measure hardness.
TDS — Miramar	533 mg/LAverage · range 474–611	2025View source ↗	Below 1,000 mg/L secondary MCLAesthetic benchmark; this does not measure hardness.
TDS — Otay	585 mg/LAverage · range 508–634	2025View source ↗	Below 1,000 mg/L secondary MCLAesthetic benchmark; this does not measure hardness.
TDS — Purchased treated water	361 mg/LAverage · range 105–513	2025View source ↗	Below 1,000 mg/L secondary MCLAesthetic benchmark; this does not measure hardness.

In drinking water, ppm ≈ mg/L, ppb ≈ µg/L and ppt ≈ ng/L. Calculated hardness in grains per US gallon (gpg) = mg/L as CaCO₃ ÷ 17.118, rounded to one decimal. ND means below the reporting limit, not zero.

MCL is an enforceable contaminant limit; MRDL is a disinfectant limit. A PHG is a health goal, not the legal limit. Lead/copper action levels use system sampling percentiles, not a safe-tap threshold. TTHM/HAA5 comparisons use locational running annual averages.

PFAS results are compound-specific. Source monitoring, entry-point samples and tap tests are different. Notification and response levels in a utility report are not maximum contaminant levels; do not infer a compliance violation from a single value. EPA PFAS benchmarks and implementation ↗

Hardness source ↗USGS hardness classification ↗

Turn your report into a plan for your home.

Choose the system size, keep useful existing equipment, and review your filtration goals.

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Next: match my home →

Source water. Mostly imported Colorado River/State Water Project blends. City plants: Alvarado, Miramar, Otay. A smaller purchased treated-water supply blends Skinner, Twin Oaks Valley and Carlsbad desalination sources. Do not confuse City Otay plant with Otay Water District.

More about your local water

What this means for your home

City of San Diego water and neighboring districts are separate systems. The City’s Otay treatment plant is not Otay Water District. Purchased treated water also has a different hardness profile.

Filter vs. softener: what each does Plan installation with your plumber

A useful local question

Is the Otay plant the same as Otay Water District?

No. This report includes the City of San Diego’s Otay treatment plant. Otay Water District is a separate supplier with its own annual report.

Sources and methodology

We keep each utility’s results separate, show the reported sample year, and distinguish averages, maxima and tap-sampling percentiles. Hardness classifications use USGS ranges. Missing data stays unknown.

City of San Diego Public Utilities Department ↗2025 utility report; each result retains its sampling year
2025 nondetected parameters supplement ↗
USGS hardness classification
EPA PFAS benchmarks and implementation

Sources checked October 25, 2026

Your water → your home → your system

Turn your report into a plan for your home.

Choose the system size, keep useful existing equipment, and review your filtration goals.

Find My Water System →

Your homeFind my system →

San Diego water quality report

Match the name on your water bill.

City of San Diego Public Utilities Department

Your water at a glance

Hardness

Disinfectant residual

TTHM

HAA5

Fluoride

Lead

Arsenic

PFAS — PFBA

The numbers behind your report

Turn your report into a plan for your home.

Your provider needs its own report.

Private well? Start with a current water test.

What this means for your home

Is the Otay plant the same as Otay Water District?

Sources and methodology

Turn your report into a plan for your home.