Daly City Water Hardness & Quality Report (2026)
Water Hardness
~120–179 mg/L
Hardestimated · not lab-verified
Source
reservoir
pH Level
7.5
neutral = 7.0
Lead
0.005 mg/L
✓ Below action level
TDS
189.7 mg/L
Est. Daily Cost
$0.40
energy & soap waste
Source: See methodology section below · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Daly City, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In Daly City | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.8 yrs | 8.5 yrs | -20% |
| Washing Machine | 9.6 yrs | 12 yrs | -20% |
| Water Heater | 12 yrs | 15 yrs | -20% |
Regional Water Comparison
How Daly City compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Daly City, California | ≈ 120–179 mg/L | 0 ppt | 🟠 Hard | reservoir |
| Parkside, California | ≈ 180+ mg/L | 7.4 ppt | 🔴 Very Hard | mixed |
| Noe Valley, California | ≈ 0–60 mg/L | 7.4 ppt | 🟢 Soft | mixed |
| Visitacion Valley, California | ≈ 120–179 mg/L | 7.5 ppt | 🟠 Hard | mixed |
| Mission District, California | ≈ 120–179 mg/L | 6.6 ppt | 🟠 Hard | mixed |
National Benchmark
How Daly City compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Daly City | ≈ 120–179 mg/L | 🟠 Moderate |
| USA National Avg | 151 mg/L | 🟠 Moderate |
| Scarsdale Top Rated | 0.02 mg/L | 🟢 None |
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What Makes Daly City's Water Unique?
Local geology and source profile
The City of Daly City Public Utilities Department serves approximately 108,599 residents in Daly City, San Mateo County, California. Water is purchased as treated surface water from the San Francisco Public Utilities Commission (SFPUC). Primary sources include the Hetch Hetchy Reservoir and Crystal Springs Reservoir, with treatment carried out at SFPUC facilities including the Sunol Valley Water Treatment Plant and the Peninsula Water Treatment Plant. No local groundwater or aquifers are used; the supply is entirely imported surface water delivered through the regional system.
The supply draws from the Tuolumne River Watershed and local Peninsula reservoirs including Crystal Springs, encompassing the granitic Sierra Nevada Batholith and Franciscan Complex formations. Igneous rocks such as granodiorite and tonalite from the Mesozoic era dominate, with subordinate sedimentary and volcanic units. This geology yields a relatively soft supply, as Sierra granite weathers to release only trace calcium and magnesium without significant carbonate content, while coastal fog and rainfall further dilute ions.
The moderately soft supply in Daly City leads to moderate scale buildup in appliances such as water heaters, dishwashers, and coffee makers, reducing efficiency over time. Laundry may feel slightly stiffer and soap lathering is somewhat reduced. Regular maintenance including descaling fixtures quarterly and flushing water heaters annually is recommended; a water softener is often suggested for households with scale-sensitive equipment to extend appliance life and improve cleaning efficiency. Daly City water meets all EPA standards with no MCL violations reported; pH is typically neutral to slightly alkaline at 7.5–8.5. The utility complies with lead and copper rules, with low action levels; no PFAS detections above guidelines are noted in recent reports. Treatment at SFPUC plants involves coagulation, filtration, chloramination, and fluoridation for pathogen removal and corrosion control.
Geology & Source: Sierra Nevada Batholith — Mesozoic granodiorite and tonalite (Hetch Hetchy watershed); Franciscan Complex formations; limited carbonate dissolution from igneous rocks; coastal dilution keeps mineralization low; soft supply
Other California Water Reports
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Frequently Asked Questions
Is Daly City's water safe to drink?
Do I need a water softener in Daly City?
How does Daly City compare to the USA average?
Data Sources & Methodology
Water quality data for Daly City is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.
Water Hardness
Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.
pH
Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.
TDS — Total Dissolved Solids
Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.
PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances
EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.
Lead
Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.
Appliance Lifespan
Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.