01The verdict: is Twin Peaks water safe?
Twin Peaks's drinking water has significant quality concerns based on EPA testing data. With a grade of B (76.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 2,915 residents using surface water (rivers, lakes, or reservoirs).
Copper is over its legal limit
Measured at 1.76 mg/L against the EPA Action Level of 1.3 mg/L. The ledger below shows how far over — and which filter removes it.
See the measurement ↓3K people, 2 systems
All figures on this page come from federal EPA compliance and testing data for the systems serving this city.
See the systems ↓2 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Twin Peaks's drinking water received a grade of B (76.8 out of 100), indicating good water quality. The city's 2 water systems serve approximately 2,915 residents using purchased surface water.
Lead levels were measured at 9.3 ppb (90th percentile), which is within EPA limits but above recommended levels. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 11 violations on record, including 3 health-based violations. 4 remain unresolved.
Twin Peaks ranks #428 out of 690 cities in California for water quality, placing it below average in the state. The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection. While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection. As a small community water system, Twin Peaks may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Twin Peaks's water
Every contaminant flagged in Twin Peaks, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Over Limit — EPA Action Level: 1.3 mg/L
Exceeds the EPA action level. Copper leaches from household plumbing — flush taps for 30 seconds before drinking, and consider a certified filter.Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 9.3 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.76 | 1.3 | mg/L | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in California
Cities ranked by compounds detected Cu Copper in California
Cities ranked by 90th-percentile copper
03Twin Peaks's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 11 violations on record, including 3 health-based violations. 4 remain unresolved.
7 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 1.1 ppb since 2000. Latest reading: 9.3 ppb (2025) — 62% of the action level. Sampled at higher-risk homes (90th percentile).
▲ Up 0.36 mg/L since 1993. The latest reading (1.8 mg/L, 2022) is over the action level. Sampled at higher-risk homes (90th percentile).
04Where Twin Peaks's water comes from
Twin Peaks's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Purchased Surface Water
Rivers, lakes, or reservoirs — more exposed to runoff, agriculture, and seasonal swings than groundwater.
Wholesale supplier
Multi-barrier treatment: coagulation, sedimentation, filtration, and disinfection to meet EPA standards.
2 systems
2 water systems, operated under private ownership.
2,915 people
Residents served across Twin Peaks's service area.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards. These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge. The system is operated by private ownership and serves approximately 2,915 people through 2 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| ALPINE WATER USERS ASSOCIATION | CA3610002 | 2,534 | Purchased Surface Water |
| STRAWBERRY LODGE MWC | CA3600301 | 381 | Groundwater |
Water bodies near Twin Peaks
As a surface-water system, these water bodies may directly influence Twin Peaks's drinking water supply.
05Pressure on Twin Peaks's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
10 federal disaster declarations on record for San Bernardino County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
San Bernardino County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Twin Peaks compares
Scores for nearby California cities on one line, with the average marked.
dashed line = California average (57/100)
Twin Peaks scores 76.8/100 — above the California average of 57/100. It outscores 7 of 10 nearby cities. Full California rankings →
42.8 / 100FSan Jose, CA
28 / 100BOakland, CA
77.9 / 100FSan Diego, CA
39.7 / 100FSacramento, CA
31.2 / 100ABurlingame, CA
89.2 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Twin Peaks's water — not generic advice.
Filter drinking & cooking water
NSF-certified water filter. Lead detected at 9.3 ppb
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for Twin Peaks alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Twin Peaks, CA tap water safe to drink?
Twin Peaks's water quality earned a grade of B (76.8/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #428 out of 690 cities tested in California.
What contaminants are in Twin Peaks's water?
Lead was measured at 9.3 ppb (90th percentile). 11 violations are on record.
How is Twin Peaks's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Twin Peaks?
While lead levels are within EPA limits, a filter adds extra protection. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Twin Peaks's water come from?
Twin Peaks's water is sourced from Purchased surface water. The city has 2 water systems serving approximately 2,915 residents.
What health violations has Twin Peaks's water system had?
Twin Peaks has 3 health-based violations on record. The most recent violation was recorded in January 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 4 violations remain unresolved.
How does Twin Peaks's water compare to other cities?
Twin Peaks ranks #428 out of 690 cities in California (better than 38% of state cities) and #9079 out of 15382 cities nationally (41th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.