Water report directory / CA
Los Angeles water guide.
Several treatment sources, with different mineral profiles.
The water profile.
LADWP 2025 report, Tables II and III; treatment-source results
| What to look at | Utility information |
|---|---|
| Los Angeles Aqueduct Filtration Plant — hardness | Average 103 mg/L as CaCO₃; range 96–117 |
| MWD Weymouth Plant — hardness | Average 234 mg/L as CaCO₃; range 189–280 |
| Los Angeles Aqueduct Filtration Plant — TDS | Average 234 mg/L; range 218–265 |
| MWD Weymouth Plant — TDS | Average 536 mg/L; range 456–617 |
Read the source column before the number.
LADWP presents separate columns for its aqueduct filtration plant, combined wells and Metropolitan Water District treatment plants. The hardness and total-dissolved-solids figures differ between those sources.
The examples above are treatment-source results, not a measurement of a particular home. Read the service-area map and the report’s source explanations with the monitoring tables.
Distinguish hardness from dissolved solids.
Hardness and TDS are separate rows for a reason. Hardness describes a property associated mainly with calcium and magnesium; TDS combines dissolved material. Use the individual mineral information when the question is taste, and the hardness result when planning for scale.
Ask the project team to record the applicable supply, household water use and any incoming-water requirements for the selected equipment.
Find your supplier.
For addresses served by Los Angeles Department of Water and Power, begin with the supplier’s published information. Confirm the supplier on your bill, especially if you live outside the city’s direct service area.
Keep the context with the figures.
The report’s service-area information and the notes explaining which monitoring tables apply to your address.
Read the ranges, sampling dates and footnotes alongside the results to understand the water supplied to your area.
For a question about your tap.
A change in taste, color or odor is a reason to contact your supplier with the details. Ask about any current advisories and the right testing method for a specific concern.
For a treatment project, keep your report and any tap-water test results together so you can discuss the right system for your home.
Bring it into the project.
Keep the report with the installation information: the address, available utilities and what you want from the water experience. For Atelier, that discussion also includes the dispenser location and nearby equipment space.