Monte Sereno, California
San Jose Water 2024 Water Quality Report (Water Boards PWS CA4310011). Hardness as CaCO3 prints as three labeled columns — mountain surface 155 ppm, groundwater 364 ppm (155–545), Valley Water 119 ppm (82–168). Total chlorine RAA 1.17 ppm. No Measure S-style ban turned up — check the sewer agency on the bill.
- Hardness (mountain surface)155 ppm (9 gpg)
- Hardness (groundwater)364 ppm (155–545)
- Hardness (Valley Water)119 ppm (82–168)
- Total chlorine1.17 ppm RAA
Best match for Monte Sereno
Salt-based water softener — confirm the district first
Check the sanitation district before installing a salt system.
Ask the agency on the sewer side of the bill before you cut a brine drain. California lets districts restrict self-regenerating units. A “banned in California” blog is not your district.
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Other options that still fit
Salt-free conditioner
A salt-free conditioner changes how scale sticks. It does not soften. Soap and spots stay closer to untreated. No brine line.
Whole-house catalytic carbon for chloramine
Catalytic carbon with a chloramine claim (NSF/ANSI 42 for chloramine). Regular chlorine carbon is the wrong box.
Under-sink reverse osmosis
The under-sink RO we actually run is Cloud RO — NSF/ANSI 58, kitchen tap, not a whole-house tank. Check the exact listing if PFAS is why you are shopping. Shop Amazon first for under-sink RO, or buy Cloud direct. Waterdrop is a tankless option if you want that path. A certifier-listed pitcher is the cheap first step. Nobody is paying for a medical claim.
Shop under-sink reverse osmosisBuy Cloud RO directShop Waterdrop reverse osmosisShop PFAS-listed pitchers
Test the tap first
A homeowner kit is a start. It is not a state-certified lab. Use a certified lab when the decision is expensive.
On the report
- Water utility
- San Jose Water
- Hardness
- Three labeled columns on the San Jose Water 2024 tables in the Year=2025 Water Boards filing. Mountain surface hardness as CaCO3 155 ppm (also 9 gpg). Groundwater 364 ppm (155–545), also 21 gpg (9–32). Valley Water surface 119 ppm (82–168), also 7 gpg (5–10). Not a blend. — San Jose Water 2024 Water Quality Report
- Disinfectant
- Total chlorine running annual average 1.17 ppm, MRDL 4.0 as Cl2. Narrative: chloramine and chlorine may be present. — San Jose Water 2024 Water Quality Report
- Brine / salt to the sewer
- Check the sanitation district before installing. No city or sanitation-district residential self-regenerating softener ban like LACSD Measure S or IEUA Ordinance § 2.6 turned up on the pages we opened. That is not a statewide ban finding. Ask the agency on the sewer bill before you cut a brine drain.
Also around here
Extra context besides the utility report and the chart above — geology, an unregulated table, or a published study. Not a second set of printed tap numbers.
- MicroplasticsWHO’s 2019 review examined studies that found microplastic particles in treated tap and bottled water in many places. That is a published-occurrence finding, not a number from this city’s water-quality report, and we do not invent a particles-per-liter count for the tap.Microplastics in drinking-water — World Health Organization
- PFASEPA’s Fifth Unregulated Contaminant Monitoring Rule required community systems this size to test 29 PFAS and lithium in 2023–2025. Open the UCMR 5 Data Finder for this PWS. This file does not invent a detection.Fifth Unregulated Contaminant Monitoring Rule — U.S. Environmental Protection Agency
Monte Sereno drinking water on this file is San Jose Water for the addresses SJW serves. San Jose Water also bills Los Gatos and Campbell — check the bill. No city or sanitation-district residential self-regenerating softener ban like LACSD Measure S or IEUA Ordinance § 2.6 turned up on the pages we opened. That is not a statewide ban finding. Ask the agency on the sewer bill before you cut a brine drain. This is not a legal opinion.
The 2024 tables print hardness as CaCO3 as three labeled columns — mountain surface 155 ppm, groundwater 364 ppm (155–545), and Valley Water 119 ppm (82–168). Total chlorine RAA 1.17 ppm. Kitchen shopping stays the Cloud RO / Waterdrop path already used on other cities if a listing is why you are looking.
Sources
- 2024 Water Quality Report (San Jose Water, opened as PWS CA4310011) — San Jose Water / State Water Resources Control Board. Accessed 2026-09-11.
Updated September 11, 2026. A city file is chemistry we can cite plus the sewer rule. No invented detections.