City water profile
Compare local ZIP estimates, evidence quality, associated public systems, and compliance history for San Luis Obispo, California.
Median indexed hardness
405PPM
2 indexed ZIPs
Range 404.5–406 PPM
City summary
San Luis Obispo has 2 published ZIP profiles across San Luis Obispo County. The indexed median is 405 PPM, compared with 189 PPM across California.
Among the 242 Californiacities with an indexed median, San Luis Obispo ranks #13from highest to lowest. Across all 678 state ZIP profiles, available estimates run from 3.3to 728.5 PPM.
The 404.5–406 PPM range shows how much the available ZIP estimates vary within the city label.
Hardness distribution
2 of 2 ZIP profiles have a hardness estimate. Bars count ZIP profiles, not households or laboratory samples.
Evidence quality
Confidence labels
Observation window: Apr 5, 2016 to Mar 2, 2023.
ZIP directory
Open a ZIP for site-level provenance and measurements.
Public water systems
PWSID CA4010009
A municipal system, in-state city, and served county all agree with this Census ZCTA.
Compliance history
No active health-based violation appears among the associated systems in the represented EPA reporting quarter. This does not mean every contaminant was tested at every tap.
No violation records are included in the current lookback window.
Practical next steps
Continue comparing
Questions people ask
The indexed city median is 405 PPM. Open the ZIP report to verify the distance and confidence behind that estimate.
Compliance history is utility-wide and cannot guarantee conditions at every tap. Check current notices and test when address-specific evidence is needed.
Choose treatment only after confirming the problem at the property. A softener targets hardness; contaminant treatment requires a matching, verified performance claim.