Your Local Water Profile: San Marino
This profile explains what the applicable water provider reported for San Marino, what those results may mean throughout a home, and where property-specific testing or inspection may still be needed.
First, confirm your water provider.
Water service can vary by address. Confirm the provider shown on your water bill before applying provider-specific results.
What the official water report says
Your water at a glance
California American Water
The report lists hardness as 113 ppm; this is moderately hard on the USGS scale.
USGS hardness scale: 0–60 soft; 61–120 moderately hard; 121–180 hard; >180 very hard, in mg/L as CaCO3.
Sunny Slope Water Company
The report lists hardness as 84.0 mg/L; this is moderately hard on the USGS scale.
USGS hardness scale: 0–60 soft; 61–120 moderately hard; 121–180 hard; >180 very hard, in mg/L as CaCO3.
San Marino Water System — compliance, as reported
The report states: “We are pleased to report that in 2025, your water met state and federal drinking water requirements. [p. 2]”
Violations or advisories, as reported: Monitoring Requirements Not Met for California American Water – San Marino: Our water system failed to monitor as required for drinking water standards during 2022 and 2023, therefore, was in violation of the regulations. During May 2022, we did not conduct follow-up monitoring for Perchlorate. An annual Perchlorate sample had a detection that was inadvertently missed. Quarterly sampling should have begun in the third quarter of 2022. The error has been corrected, and samples are being collected quarterly since May of 2023 at one source and July of 2025 at the other. [p. 17]
Sunny Slope Water Company — compliance, as reported
The report states: “We are proud to report that during 2024, the drinking water provided by SSWC met or surpassed all federal and state drinking water standards. [p. 2]”
The Three C's — 1 of 3
Chemistry
What does this water tend to do in a home?
San Marino Water System
Total Hardness (as CaCO3)
The utility reported: 113 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Total Hardness (as CaCO3)
The utility reported: 234 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Total Hardness (as CaCO3)
The utility reported: 6.6 grains per gallon
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Total Hardness (as CaCO3)
The utility reported: 14 grains per gallon
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Alkalinity as CaCO3
The utility reported: 180 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Alkalinity as CaCO3
The utility reported: 110 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Total Dissolved Solids
The utility reported: 229 ppm
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Total Dissolved Solids
The utility reported: 536 ppm
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Lead 90th Percentile
The utility reported: 0 ppb
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Copper 90th Percentile
The utility reported: 0.226 ppm
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Chloramines
The utility reported: 2.6 ppm
DISINFECTANTS & DISINFECTION BY PRODUCTS · report p. 5 · official report
Chlorine
The utility reported: 1.27 ppm
DISINFECTANTS & DISINFECTION BY PRODUCTS · report p. 5 · official report
Sunny Slope Water Company
Alkalinity as CaCO3
The utility reported: 120 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Total Dissolved Solids
The utility reported: 240 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Chloride (Cl-)
The utility reported: 12 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Sulfate (SO42)
The utility reported: 30 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Lead (Pb)
The utility reported: Not detected at the report's stated reporting limit µg/L
INORGANIC CHEMICALS · report p. 8 · official report
Chlorine Residual
The utility reported: 0.93 mg/L
DISINFECTANT AND DISINFECTION BY-PRODUCTS · report p. 8 · official report
The Three C's — 2 of 3
Contaminants
What was reported, and what do the applicable standards mean?
Legal limit — maximum contaminant level (MCL)
The highest level legally allowed in public drinking water under the applicable rule. Do not use MCL as a generic label for goals, action levels, notification levels, or independent guidelines. It is different from a non-enforceable health goal.
California health goal — public health goal (PHG)
A non-enforceable health-protective target developed for standard-setting context. It is not the California legal limit.
Federal health goal — maximum contaminant level goal (MCLG)
A non-enforceable EPA public-health target used in setting standards. It is not the legal limit.
Legal disinfectant-residual limit — maximum residual disinfectant level (MRDL)
The highest level of a drinking-water disinfectant allowed under the applicable rule. It is not an MCL for a contaminant.
San Marino Water System — regulated contaminants reported as detected (27)
Lead
The utility reported: 0 ppb
Reported range: ND - 1
AL: 15 · Health goal (MCLG): 0.2 — not an enforceable limit
Violation per report: No
Typical source, per the report: Corrosion of household plumbing systems.
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Copper
The utility reported: 0.226 ppm
Reported range: ND - 0.49
AL: 1.3 · Health goal (MCLG): 0.3 — not an enforceable limit
Violation per report: No
Typical source, per the report: Corrosion of household plumbing systems.
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Total Coliform
The utility reported: 1.1%
TT: Less than 5% · Health goal (MCLG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Naturally present in the environment and are used as an indicator that other, potentially harmful, waterborne pathogens may be present or that a potential pathway exists through which contamination may enter the drinking water distribution system
REVISED TOTAL COLIFORM RULE · report p. 4 · official report
E. Coli
The utility reported: 0
TT: No confirmed samples · Health goal (MCLG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Human and animal fecal waste.
REVISED TOTAL COLIFORM RULE · report p. 4 · official report
Turbidity
The utility reported: 0.06 NTU
TT: Single result >1 NTU · Health goal (MCLG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Soil runoff.
TURBIDITY · report p. 4 · official report
Turbidity
The utility reported: 100% NTU
TT: At least 95% of samples <0.3 NTU · Health goal (MCLG): NA — not an enforceable limit
Violation per report: No
Typical source, per the report: Soil runoff.
TURBIDITY · report p. 4 · official report
Haloacetic Acids
The utility reported: 2.7 ppb
Reported range: ND to 5.4
Legal limit (MCL): 60 · Health goal (MCLG): NA — not an enforceable limit
Violation per report: No
Typical source, per the report: By-product of drinking water disinfection.
DISINFECTANTS & DISINFECTION BY PRODUCTS · report p. 5 · official report
Total Trihalomethanes
The utility reported: 19 ppb
Reported range: 2.0 to 34
Legal limit (MCL): 80 · Health goal (MCLG): NA — not an enforceable limit
Violation per report: No
Typical source, per the report: By-product of drinking water disinfection.
DISINFECTANTS & DISINFECTION BY PRODUCTS · report p. 5 · official report
Chloramines
The utility reported: 2.6 ppm
Reported range: 1.1 to 3.1
MRDL: 4 · Health goal (MRDLG): 4 — not an enforceable limit
Violation per report: No
Typical source, per the report: Water additive used to control microbes.
DISINFECTANTS & DISINFECTION BY PRODUCTS · report p. 5 · official report
Chlorine
The utility reported: 1.27 ppm
Reported range: 1.18 to 1.59
MRDL: 4 · Health goal (MRDLG): 4 — not an enforceable limit
Violation per report: No
Typical source, per the report: Water additive used to control microbes.
DISINFECTANTS & DISINFECTION BY PRODUCTS · report p. 5 · official report
Aluminum
The utility reported: 0.008 ppm
Reported range: ND to 0.067
Legal limit (MCL): 1 · Health goal (PHG): 0.6 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Aluminum (MWD Weymouth)
The utility reported: 0.096 ppm
Reported range: ND to 0.1
Legal limit (MCL): 1 · Health goal (PHG): 0.6 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Arsenic
The utility reported: 0.6 ppb
Reported range: ND to 2.8
Legal limit (MCL): 10 · Health goal (PHG): 0.004 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; runoff from orchards; glass and electronic production wastes.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Barium
The utility reported: 0.02 ppm
Reported range: 0.015 to 0.023
Legal limit (MCL): 1 · Health goal (PHG): 2 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; discharges of oi; drilling wastes and metal refineries.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Barium (MWD Weymouth)
The utility reported: 0.13 ppm
Reported range: 0.13
Legal limit (MCL): 1 · Health goal (PHG): 2 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; discharges of oi; drilling wastes and metal refineries.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Chromium
The utility reported: 8.2 ppb
Reported range: 5.4 to 10
Legal limit (MCL): 50 · Health goal (PHG): 100 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; discharge from steel & pulp mills as well as chrome plaiting .
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Fluoride
The utility reported: 0.9 ppm
Reported range: 0.8 to 1
Legal limit (MCL): 2 · Health goal (PHG): 1 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; water additive which promotes strong teeth; discharge from fertilizer and aluminum factories.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Fluoride (MWD Weymouth)
The utility reported: 0.7 ppm
Reported range: 0.5 to 0.8
Legal limit (MCL): 2 · Health goal (PHG): 1 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; water additive which promotes strong teeth; discharge from fertilizer and aluminum factories.
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Hexavalent Chromium
The utility reported: 8.6 ppb
Reported range: 5.3 to 10
Legal limit (MCL): 10 · Health goal (PHG): 0.02 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits; transformation of naturally occurring trivalent chromium to hexavalent chromium by natural processes & human activities such as discharges from electroplating factories, leather tanneries & wood preservation,
PRIMARY REGULATED SUBSTANCES · report p. 6 · official report
Nitrate as N
The utility reported: 3.4 ppm
Reported range: 1.0 to 4.7
Legal limit (MCL): 10 · Health goal (PHG): 10 — not an enforceable limit
Violation per report: No
Typical source, per the report: Fertilizer runoff; leaching from septic tanks, sewage; erosion of natural deposits.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Perchlorate
The utility reported: 0.3 ppb
Reported range: ND to 1.2
Legal limit (MCL): 6 · Health goal (PHG): 1 — not an enforceable limit
Violation per report: No
Typical source, per the report: Industrial waste discharge.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Tetrachloroethylene (PCE)
The utility reported: 0.62 ppb
Reported range: ND to 2.1
Legal limit (MCL): 5 · Health goal (PHG): 0.06 — not an enforceable limit
Violation per report: No
Typical source, per the report: Discharge from factories, dry cleaners, & auto shops.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Trichlorofluoromethane (TCE)
The utility reported: 1.3 ppb
Reported range: ND to 4.4
Legal limit (MCL): 5 · Health goal (PHG): 1.7 — not an enforceable limit
Violation per report: No
Typical source, per the report: Discharge from metal degreasing sites & other factories.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Gross Alpha Particle Activity
The utility reported: 0.9 pCi/L
Reported range: ND to 2.7
Legal limit (MCL): 15 · Health goal (PHG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Decay of natural and man-made deposits.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Gross Beta Particle Activity (MWD Weymouth)
The utility reported: Not detected at the report's stated reporting limit pCi/L
Reported range: ND to 5
Legal limit (MCL): 50 · Health goal (PHG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Decay of natural and man-made deposits.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Uranium
The utility reported: 2.2 pCi/L
Reported range: 1.4 to 3.8
Legal limit (MCL): 20 · Health goal (PHG): 0.43 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Uranium (MWD Weymouth)
The utility reported: Not detected at the report's stated reporting limit pCi/L
Reported range: ND to 3
Legal limit (MCL): 20 · Health goal (PHG): 0.43 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
San Marino Water System — unregulated monitoring and secondary (aesthetic) records (22)
Unregulated means monitored without an applicable enforceable legal limit (MCL) — it does not mean unimportant or illegal. Secondary records address aesthetic, cosmetic, or technical effects such as taste, odor, staining, or scale, and are not automatically primary health standards.
Chloride
The utility reported: 12 ppm
Reported range: 8.2 to 17
Typical source, per the report: Erosion or leaching of natural deposits
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Chloride (MWD Weymouth)
The utility reported: 92 ppm
Reported range: 86 to 98
Typical source, per the report: Erosion or leaching of natural deposits
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Color
The utility reported: Not detected at the report's stated reporting limit units
Reported range: ND
Typical source, per the report: Naturally occurring organic materials
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Color (MWD Weymouth)
The utility reported: 1 units
Reported range: 1
Typical source, per the report: Naturally occurring organic materials
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Iron
The utility reported: 13 ppb
Reported range: ND to 74
Typical source, per the report: Leaching from natural deposits
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Specific Conductance
The utility reported: 397 umhos/cm
Reported range: 370 to 420
Typical source, per the report: Substances that form ions when in water; Seawater influence
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Specific Conductance (MWD Weymouth)
The utility reported: 868 umhos/cm
Reported range: 754 to 981
Typical source, per the report: Substances that form ions when in water; Seawater influence
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Sulfate
The utility reported: 23 ppm
Reported range: 16 to 41
Typical source, per the report: Runoff/leaching from natural deposits; Industrial wastes
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Sulfate (MWD Weymouth)
The utility reported: 176 ppm
Reported range: 139 to 212
Typical source, per the report: Runoff/leaching from natural deposits; Industrial wastes
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Total Dissolved Solids
The utility reported: 229 ppm
Reported range: 210 to 250
Typical source, per the report: Runoff/leaching from natural deposits
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Total Dissolved Solids (MWD Weymouth)
The utility reported: 536 ppm
Reported range: 456 to 617
Typical source, per the report: Runoff/leaching from natural deposits
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Turbidity
The utility reported: 0.14 NTU
Reported range: ND to 0.3
Typical source, per the report: Soil runoff
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Bromate (MWD Weymouth)
The utility reported: 3.0 ppb
Typical source, per the report: Byproduct of drinking water disinfection.
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Boron (MWD Weymouth)
The utility reported: 0.13 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Chlorate (MWD Weymouth)
The utility reported: 31 ppb
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Potassium (MWD Weymouth)
The utility reported: 4.4 ppm
Typical source, per the report: Salt present in the water; naturally occurring.
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Total Organic Carbon (MWD Weymouth)
The utility reported: 2.5 ppm
Typical source, per the report: Naturally Occurring
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Perfluorooctanesulfonic acid (PFOS)
The utility reported: 0.6 ppt
Reported range: ND to 9
UNREGULATED CONTAMINANT MONITORING (UCMR 5) · report p. 10 · official report
Perfluorobutanoic acid (PFBA)
The utility reported: 0.8 ppt
Reported range: ND to 5
Typical source, per the report: Manufactured chemical; used in products for stain, grease, heat and water resistance
UNREGULATED CONTAMINANT MONITORING (UCMR 5) · report p. 10 · official report
Perfluorohexanoic acid (PFHxA)
The utility reported: 0.2 ppt
Reported range: ND to 1.3
Typical source, per the report: Manufactured chemical; used in products for stain, grease, heat and water resistance
UNREGULATED CONTAMINANT MONITORING (UCMR 5) · report p. 10 · official report
Perfluoropentanoic acid (PFPeA)
The utility reported: 0.09 ppt
Reported range: ND to 1.3
Typical source, per the report: Manufactured chemical; used in products for stain, grease, heat and water resistance
UNREGULATED CONTAMINANT MONITORING (UCMR 5) · report p. 10 · official report
Lithium
The utility reported: 9.3 ppb
Reported range: ND to 92
Typical source, per the report: Naturally occurring with multiple commercial uses
UNREGULATED CONTAMINANT MONITORING (UCMR 5) · report p. 10 · official report
Sunny Slope Water Company — regulated contaminants reported as detected (11)
Chlorine Residual
The utility reported: 0.93 mg/L
Reported range: 0.08 - 1.94
MRDL: 4 · Health goal (MRDLG): 4 — not an enforceable limit
Violation per report: No
Typical source, per the report: Drinking water disinfectant
DISINFECTANT AND DISINFECTION BY-PRODUCTS · report p. 8 · official report
Total Trihalomethanes (TTHM)
The utility reported: 2.34 µg/L
Reported range: ND - 6.20
Legal limit (MCL): 80
Violation per report: No
Typical source, per the report: By-product of drinking water chlorination
DISINFECTANT AND DISINFECTION BY-PRODUCTS · report p. 8 · official report
Haloacetic Acids (five) (HAA5)
The utility reported: 0.89 µg/L
Reported range: ND - 7.10
Legal limit (MCL): 60
Violation per report: No
Typical source, per the report: By-product of drinking water chlorination
DISINFECTANT AND DISINFECTION BY-PRODUCTS · report p. 8 · official report
Copper (Cu)
The utility reported: 0.45 mg/L
Reported range: ND - 0.79
AL: 1.3 · Health goal (PHG): 0.3 — not an enforceable limit
Violation per report: No
Typical source, per the report: Corrosion of household plumbing system
INORGANIC CHEMICALS · report p. 8 · official report
Fluoride (F)
The utility reported: 1 mg/L
Reported range: 1
Legal limit (MCL): 2 · Health goal (PHG): 1 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits
INORGANIC CHEMICALS · report p. 8 · official report
Nitrate (NO3) as Nitrogen (N)
The utility reported: 2.87 mg/L
Reported range: 2.0 - 3.8
Legal limit (MCL): 10 · Health goal (PHG): 10 — not an enforceable limit
Violation per report: No
Typical source, per the report: Leaching from fertilizer use
INORGANIC CHEMICALS · report p. 8 · official report
Chromium, Hexavalent (Cr+6)
The utility reported: 7.53 µg/L
Reported range: 5.70 - 9.60
Legal limit (MCL): 10 · Health goal (PHG): 0.2 — not an enforceable limit
Violation per report: No
Typical source, per the report: Naturally present in the environment ; industrial wastes
INORGANIC CHEMICALS · report p. 8 · official report
Perchlorate (ClO-4)
The utility reported: 1.4 µg/L
Reported range: 1.1 - 1.5
Legal limit (MCL): 6 · Health goal (PHG): 1 — not an enforceable limit
Violation per report: No
Typical source, per the report: Naturally-occurring/man-made from aerospace/industrial
INORGANIC CHEMICALS · report p. 8 · official report
Gross Alpha Activity
The utility reported: 5.81 pCi/L
Reported range: 3.65 - 8.17
Legal limit (MCL): 15 · Health goal (MCLG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits
RADIOACTIVITY · report p. 8 · official report
Combined Radium
The utility reported: 0.25 pCi/L
Reported range: 0.159 - 0.389
Legal limit (MCL): 5 · Health goal (MCLG): 0 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits
RADIOACTIVITY · report p. 8 · official report
Uranium (U)
The utility reported: 0.61 pCi/L
Reported range: 0.61
Legal limit (MCL): 20 · Health goal (PHG): 0.43 — not an enforceable limit
Violation per report: No
Typical source, per the report: Erosion of natural deposits
RADIOACTIVITY · report p. 8 · official report
Sunny Slope Water Company — unregulated monitoring and secondary (aesthetic) records (5)
Unregulated means monitored without an applicable enforceable legal limit (MCL) — it does not mean unimportant or illegal. Secondary records address aesthetic, cosmetic, or technical effects such as taste, odor, staining, or scale, and are not automatically primary health standards.
Bicarbonate (HCO3)
The utility reported: 150 mg/L
Reported range: 150
Typical source, per the report: Runoff/leaching from natural deposits
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Specific Conductance
The utility reported: 370 µmho/cm
Reported range: 370
Typical source, per the report: Substances that form ions in water
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Boron (B)
The utility reported: 160 µg/L
Reported range: 160
Typical source, per the report: Runoff/leaching from natural deposits
METALS · report p. 8 · official report
Odor-Threshold
The utility reported: 1 Units
Reported range: 1.00
Typical source, per the report: Naturally-occurring organic materials
OTHER · report p. 8 · official report
Turbidity
The utility reported: 0.2 NTU
Reported range: 0.10 - 0.43
Typical source, per the report: Erosion of natural deposits/runoff
OTHER · report p. 8 · official report
The Three C's — 3 of 3
Corrosion
What conditions could influence pipes, fixtures, and a water heater?
San Marino Water System
Alkalinity as CaCO3
The utility reported: 180 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Alkalinity as CaCO3
The utility reported: 110 ppm
OTHER SUBSTANCES OF INTEREST · report p. 9 · official report
Lead 90th Percentile
The utility reported: 0 ppb
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Copper 90th Percentile
The utility reported: 0.226 ppm
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Lead
The utility reported: 0 ppb
Reported range: ND - 1
Typical source, per the report: Corrosion of household plumbing systems.
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Copper
The utility reported: 0.226 ppm
Reported range: ND - 0.49
Typical source, per the report: Corrosion of household plumbing systems.
LEAD AND COPPER MONITORING PROGRAM · report p. 3 · official report
Gross Alpha Particle Activity
The utility reported: 0.9 pCi/L
Reported range: ND to 2.7
Typical source, per the report: Decay of natural and man-made deposits.
PRIMARY REGULATED SUBSTANCES · report p. 7 · official report
Chloride (MWD Weymouth)
The utility reported: 92 ppm
Reported range: 86 to 98
Typical source, per the report: Erosion or leaching of natural deposits
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Sulfate (MWD Weymouth)
The utility reported: 176 ppm
Reported range: 139 to 212
Typical source, per the report: Runoff/leaching from natural deposits; Industrial wastes
SECONDARY REGULATED SUBSTANCES · report p. 8 · official report
Sunny Slope Water Company
Alkalinity as CaCO3
The utility reported: 120 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Chloride (Cl-)
The utility reported: 12 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Sulfate (SO42)
The utility reported: 30 mg/L
GENERAL CHEMICAL ANALYSES · report p. 8 · official report
Lead (Pb)
The utility reported: Not detected at the report's stated reporting limit µg/L
INORGANIC CHEMICALS · report p. 8 · official report
Gross Alpha Activity
The utility reported: 5.81 pCi/L
Reported range: 3.65 - 8.17
Typical source, per the report: Erosion of natural deposits
RADIOACTIVITY · report p. 8 · official report
Whole-Home Relevance
What this may mean throughout your home
Local conditions can be relevant to equipment and fixtures — actual effects depend on your property.
Water heater (tank and tankless)
- What the local report can tell us
- The report's hardness and mineral values above are the system-level inputs most relevant to scale and sediment where water is heated.
- What a homeowner may notice
- Hardness minerals can contribute to scale on heating surfaces, sediment in tanks, and more frequent flushing or descaling needs.
- What the report cannot tell us
- Property-specific outcomes — actual effects depend on temperature, use, equipment design, installation, maintenance, and property plumbing.
- Responsible next step
- Inspect the actual water heater and plumbing when symptoms involve hot-water odor, scale, sediment, corrosion, flow, noise, or repeated service demand.
Dishwasher and washing machine
- What the local report can tell us
- Reported hardness and secondary (aesthetic) records are the relevant system-level context for spotting and residue.
- What a homeowner may notice
- Hard water can change soap behavior and may contribute to spotting on dishes and residue in laundry.
- What the report cannot tell us
- Property-specific outcomes — actual effects depend on temperature, use, equipment design, installation, maintenance, and property plumbing.
- Responsible next step
- Inspect the actual water heater and plumbing when symptoms involve hot-water odor, scale, sediment, corrosion, flow, noise, or repeated service demand.
Pipes, fixtures, faucets, and supply lines
- What the local report can tell us
- The corrosion-related inputs above (such as pH) describe the water entering the property — not the condition of any specific plumbing.
- What a homeowner may notice
- Mineral deposits can appear on aerators and fixtures; corrosion outcomes depend on materials, age, and water conditions together.
- What the report cannot tell us
- Property-specific outcomes — actual effects depend on temperature, use, equipment design, installation, maintenance, and property plumbing.
- Responsible next step
- Inspect the actual water heater and plumbing when symptoms involve hot-water odor, scale, sediment, corrosion, flow, noise, or repeated service demand.
Drinking and cooking water
- What the local report can tell us
- The contaminant records above show what the utility reported for the system and period, with each benchmark type labeled.
- What a homeowner may notice
- Taste, odor, or aesthetic preferences can be noticeable even when health-based standards are met.
- What the report cannot tell us
- Property-specific outcomes — actual effects depend on temperature, use, equipment design, installation, maintenance, and property plumbing.
- Responsible next step
- Inspect the actual water heater and plumbing when symptoms involve hot-water odor, scale, sediment, corrosion, flow, noise, or repeated service demand.
Decision Pathways
Treatment pathways to evaluate
Treatment is a decision pathway, not a product conclusion — no equipment can be responsibly chosen from city-level data alone.
The evaluation sequence we follow, in order:
- 1Define the concern
- 2Verify utility-level and home-specific evidence
- 3Choose point of treatment
- 4Verify the exact certified reduction claim for the exact model
- 5Review tradeoffs and maintenance
Water filtration
- Objective it can address
- Specific substances or aesthetic conditions (taste, odor, chlorine character).
- Point of treatment
- Point of entry or point of use, depending on the objective.
- Limitations to verify
- A filter works only for the conditions and reduction claims its exact design and certification support — filtration does not soften water.
Certification note: a standard number alone doesn't prove a product reduces every contaminant — the exact model's certified claim must match your objective.
Water softening
- Objective it can address
- Hardness minerals (calcium and magnesium) and the scale they can contribute to.
- Point of treatment
- Typically point of entry, confirmed by evaluation.
- Limitations to verify
- Softening primarily exchanges hardness minerals — it is not a universal contaminant-removal device.
Certification note: a standard number alone doesn't prove a product reduces every contaminant — the exact model's certified claim must match your objective.
Reverse osmosis
- Objective it can address
- Specified dissolved substances at a dedicated outlet, commonly drinking and cooking water.
- Point of treatment
- Typically point of use.
- Limitations to verify
- Produces a reject-water stream and needs pressure and maintenance; verify the exact NSF/ANSI 58 reduction claims for the exact model. It is not automatically the best system for every home.
Certification note: a standard number alone doesn't prove a product reduces every contaminant — the exact model's certified claim must match your objective.
When testing is the right next step
Use a certified laboratory when the concern is tap-specific, property-specific, or not resolved by the utility report.
When inspection is the right next step
Inspect the actual water heater and plumbing when symptoms involve hot-water odor, scale, sediment, corrosion, flow, noise, or repeated service demand.
Evidence You Can Check
Official reports, sources, and methodology
Official report — San Marino Water System
2025 Annual Water Quality Report Summary · data year 2025 · Current 2025 monitoring cycle
View the 2025 San Marino Water System Consumer Confidence ReportSource water, per the report: The San Marino Water System is primarily served by groundwater sources in the Main San Gabriel and Raymond Basins (77%). Additional water supplies are purchased from Metropolitan Water District of Southern California (MWDSC) via the Weymouth Treatment Plant (23%). MWDSC’s sources of raw surface water are the Sacramento River Delta and Colorado River.
Official report — Sunny Slope Water Company
2024 CONSUMER CONFIDENCE REPORT · data year 2024 · 2024 data retained; monitor for the next official update
View the 2024 Sunny Slope Water Company Consumer Confidence ReportSource water, per the report: Sunny Slope Water Company’s water supply comes from five (5) groundwater wells located within the Main San Gabriel Basin and the Raymond Basin. A portion of water from the Raymond Basin goes through the Microvi nitrate removal plant, following the Liquid-Phase Granular Activated Carbon (LGAC) filtration plant, which removes volatile organic compounds (VOCs).
Nearby community water profiles
Property-Specific Next Step
Request a Water Quality Evaluation
Request a water-heater and water-quality evaluation tailored to the property, equipment, and homeowner objective.
A property-specific evaluation confirms your goals, provider, tap conditions, plumbing, equipment, installation, and maintenance before any treatment recommendation — this profile alone is never used to prescribe equipment.
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