San Francisco

Yosemite granite. A 160-mile journey to your tap.

Hetch Hetchy Reservoir in Yosemite National Park (primary, ~85%) — SFPUC (SF Public Utilities Commission); supplemented by local groundwater (15%). 160-mile Hetch Hetchy aqueduct. Snowmelt from Sierra Nevada.. Sierra Nevada granite — Yosemite. Hetch Hetchy Reservoir formed by O'Shaughnessy Dam (1923) in Tuolumne River canyon. Pristine High Sierra granite watershed. Soft water from granite. PFAS from military installations (Treasure Island, former Hunters Point Naval Shipyard).

3.2°dH

Hardness

14 mg/L

Calcium

Political grade

Drug traces

Cocaine 0.0028 μg/L —Benzoylecgonine 0.0058 μg/L —Amphetamine 0.00038 μg/L —Methamphetamine 0.00088 μg/L —Metformin 0.028 μg/L —Caffeine 0.018 μg/L —Ibuprofen 0.0022 μg/L —Hardness 3.2°dHpH 7.5Calcium 14 mg/LNitrate 0.42 mg/LCocaine 0.0028 μg/L —Benzoylecgonine 0.0058 μg/L —Amphetamine 0.00038 μg/L —Methamphetamine 0.00088 μg/L —Metformin 0.028 μg/L —Caffeine 0.018 μg/L —Ibuprofen 0.0022 μg/L —Hardness 3.2°dHpH 7.5Calcium 14 mg/LNitrate 0.42 mg/LCocaine 0.0028 μg/L —Benzoylecgonine 0.0058 μg/L —Amphetamine 0.00038 μg/L —Methamphetamine 0.00088 μg/L —Metformin 0.028 μg/L —Caffeine 0.018 μg/L —Ibuprofen 0.0022 μg/L —Hardness 3.2°dHpH 7.5Calcium 14 mg/LNitrate 0.42 mg/L

Taste Profile

Yosemite granite. A 160-mile journey to your tap.

San Francisco's water travels 160 miles from Hetch Hetchy Reservoir — a glacially carved valley in Yosemite National Park, flooded in 1923 over John Muir's fierce objection — through a gravity-fed aqueduct across the Central Valley. At 3.2°dH, it is very soft, carrying almost no minerals from the pristine Sierra Nevada granite of its source. Calcium is 14 mg/L — roughly one-sixth of Zurich, one-quarter of London. The softness makes Hetch Hetchy water brilliant for brewing and exceptional for revealing the full aromatic complexity of high-altitude single-origin coffee. The water is so clean at source that SFPUC's primary treatment challenge is corrosion control — soft water is slightly aggressive toward pipes — rather than contaminant removal.

Tasting notes

very light bodypure granite characterexceptionally cleanneutral pHcoffee-perfect softness

Body

Light body

Hardness

Soft — 0–7°dH

Finish

Short and clean. Silica gives the faintest mineral edge.

Pairs with

—Blue Bottle pour-over
—Dungeness crab
—Sourdough bread
—California Chardonnay

Water Memory

The valley John Muir died to save — and lost.

Hetch Hetchy Valley in Yosemite National Park was once described by John Muir as even more beautiful than Yosemite Valley itself — a glacially carved granite canyon with waterfalls, meadows, and the Tuolumne River. In 1913, after one of the first great environmental battles in American history, Congress passed the Raker Act authorizing San Francisco to dam it. O'Shaughnessy Dam was completed in 1923. Muir, who had fought the dam with extraordinary passion, died six months after the Act passed, widely believed heartbroken. The water that flows from the reservoir bears his defeat. The debate has never fully ended — environmental groups periodically propose restoration, estimating the valley could be drained and revegetated. SFPUC responds that no comparable alternative source exists for 2.7 million Bay Area residents.

“Dam Hetch Hetchy! As well dam for water-tanks the people's cathedrals and churches, for no holier temple has ever been consecrated by the heart of man.”
John Muir, 1912 — The Yosemite

Geological memory

The Sierra Nevada is a tilted granite block — the largest exposed granite batholith in North America — uplifted and glacially carved over the past 3 million years. Hetch Hetchy sits at 3,800 feet elevation, carved by the Tuolumne River and shaped by repeated glacial advances. The granite is resistant to chemical weathering, producing very soft, silica-bearing water. Sierra Nevada snowpack feeds the reservoir from October through June — climate change is reducing this snowpack, threatening long-term supply reliability. The 160-mile Hetch Hetchy Aqueduct, completed 1934, is gravity-fed entirely — no pumps required for the majority of its length, one of the most energy-efficient urban water systems in the world.

Political memory

SFPUC is a department of the City and County of San Francisco — the water system is publicly owned and has never been privatised. The federal Raker Act of 1913, which authorised the dam, contains an unusual clause explicitly prohibiting private sale of Hetch Hetchy electricity — a provision San Francisco has respected. The PFAS contamination in Bay Area water supply is a federal military legacy — Treasure Island Naval Station and Hunters Point Naval Shipyard used AFFF firefighting foam for decades, contaminating local groundwater. The Navy has been ordered to clean up but remediation proceeds slowly. The Tenderloin drug crisis — methamphetamine, fentanyl, open drug scenes — is a city governance and public health failure that the water chemistry records but cannot solve.

Cultural memory

San Francisco's relationship with water is existential — a city on a peninsula with almost no local freshwater, built during the Gold Rush on audacity, resourcefulness, and the willingness to engineer on a grand scale. The 1906 earthquake destroyed much of the city but it was the fire — fuelled by broken water mains — that completed the catastrophe. Hetch Hetchy was built partly in response: a water system that would survive an earthquake. The city's famous fog, which drifts in through the Golden Gate from the Pacific, is a form of atmospheric water — it irrigates the Marin Headlands and the Presidio, waters the eucalyptus groves, and is, in its own way, part of San Francisco's hydrology.

Water Politics

Overall

Transparency — public data access9/10

Infrastructure — pipe & treatment quality8/10

Source protection — watershed defence9/10

SFPUC operates one of North America's finest source-water systems — Hetch Hetchy in Yosemite is the standard against which other municipal supplies are measured. The water is excellent, the infrastructure is largely modern (post-Loma Prieta earthquake upgrades completed 2019), and reporting is comprehensive. PFAS from military legacy sites and at-tap lead risk in Victorian buildings are manageable concerns. The city's drug crisis is visible in the water chemistry but is a social governance failure, not a water system failure.

Failures

×Legacy military PFAS contamination at Treasure Island and Hunters Point Naval Shipyard affects Bay Area groundwater supplements
×Victorian-era buildings (pre-1986) may have lead solder — soft water increases leaching risk
×Sierra Nevada snowpack reduction under climate change threatens long-term supply reliability
×Hetch Hetchy reservoir controversy — valley remains flooded despite restoration proposals
×Tenderloin drug crisis produces fentanyl and methamphetamine signals in wastewater

Achievements

✓Hetch Hetchy source — Yosemite National Park, 3,800ft elevation, zero industrial input
✓160-mile gravity-fed aqueduct — minimal pumping energy, exceptional engineering
✓Post-Loma Prieta seismic upgrade program completed 2019 — $4.8 billion infrastructure investment
✓NELAP CA01310 accreditation — full parameter testing published annually
✓Very low PFAS at source — 0.88 ng/L total, well within all standards
✓Water energy recovery — gravity-fed aqueduct generates hydroelectric power en route

What San Francisco must do

Commission independent analysis of Hetch Hetchy ecological restoration feasibility with climate-adjusted water supply modeling. Mandate at-tap lead testing in pre-1986 buildings with results published by address. Increase Navy PFAS remediation timelines at Treasure Island and Hunters Point. Fund wastewater-based epidemiology program to track drug crisis indicators for public health response.