Purity specification
UPW Is Held Near the Physical Limit of Pure Water
Leading-edge UPW sits at 18.2 megohm-centimeters, the resistivity of water with no dissolved ions at all, and the specification tightens at every node as a harmless particle becomes a killer defect.
Pharmaceutical water for injection, the nearest comparison, is orders of magnitude less pure by resistivity and particle count. The specification is set by SEMI F63 and each fab's own limits.
| Parameter | Leading-edge UPW | Drinking water | Effect in the fab |
|---|---|---|---|
| Resistivity | 18.2 MΩ·cm (theoretical maximum for pure water at 25°C) | 0.02 to 0.1 MΩ·cm | Effectively zero dissolved ions; metal ions at parts per billion (ppb) cause device failure |
| Total organic carbon (TOC) | Under 1 ppb | Under 4,000 ppb (EPA limit) | Organics contaminate photoresist and fog EUV optics |
| Particles | Under 1 per mL at 0.05 µm and larger | Millions per mL | At 3nm a 50nm particle is many times the feature it lands on |
| Dissolved oxygen | Under 1 ppb | About 8,000 ppb | Grows native oxide on silicon during cleaning |
| Bacteria | Under 1 CFU per 100 mL | Under 500 CFU per 100 mL | Biofilm sheds particles and organics into the loop |
| Silica | Under 0.5 ppb | 1,000 to 20,000 ppb | Deposits during drying; shifts threshold voltage |
| Metal ions (Na, K, Ca, Fe, Cu) | 0.01 to 0.1 ppb per species | Hundreds to thousands of ppb | Deep-level traps: junction leakage, DRAM retention loss |
Treatment train
Six Stages, Each Removing One Class of Contaminant
UPW comes from a train in its own utility building next to the fab, and it degrades in the pipes unless it keeps moving, so the final stages run as a loop that recirculates and re-polishes water around the fab continuously.
| Stage | Process | Removes | Equipment and suppliers |
|---|---|---|---|
| 1. Pre-treatment | Coagulation, multimedia filtration, activated carbon, softening | Suspended solids, chlorine, chloramines, hardness | Sand filters, carbon beds, softening resin, antiscalant |
| 2. Reverse osmosis (RO) | Two-pass high-pressure membrane filtration | 95% to 99% of dissolved ions; bacteria; colloids | Spiral-wound polyamide membranes (DuPont FilmTec, Toray, Hydranautics) |
| 3. Electrodeionization (EDI) | Ion exchange resin regenerated continuously by a DC field | Residual ions, silica and CO2 to ppb levels | Ionpure (Xylem), SnowPure, Veolia modules |
| 4. UV oxidation | 185nm UV oxidizes organics to CO2; 254nm UV sterilizes | TOC to under 1 ppb; bacteria | Low-pressure mercury lamps or UV-LED arrays |
| 5. Degassing | Vacuum towers or hydrophobic membrane contactors | Dissolved O2 to under 1 ppb; CO2; N2 | 3M Liqui-Cel contactors, vacuum towers |
| 6. Final polishing | Mixed-bed ion exchange, then ultrafiltration at point of use | Ions to under 0.1 ppb; particles to 0.02 to 0.05 µm | Mixed-bed vessels, hollow-fiber UF, recirculating loop |
The design depends on the source: municipal supply, groundwater, river intake and reclaimed wastewater each give a different feed. Chemical supply to the same tools is on Chemical Delivery.
Use and recycling
Water Use and Recycling Benchmarks
| Metric | Value | Context |
|---|---|---|
| TSMC Arizona Fab 1 city water | ~4.75M gallons a day | Reported in August 2026; Phoenix projects about 17.2 million gallons a day for three fabs |
| TSMC Arizona recycling | ~65% today; 85-90% from 2028 | The industrial water reclamation plant treats streams that cannot be recycled today |
| Best-in-class reuse | 80%+ | Intel Oregon; Samsung Taylor targets about 75% of process water |
| Evaporation loss | ~15% | Mostly cooling towers; water that cannot be reclaimed |
| UPW per 300mm wafer | ~2,000-5,000 gallons | Industry estimate; rises with cleaning, CMP and wet etch steps at advanced nodes |
| UPW system capital | $200-500M | Industry estimate for a leading-edge fab; recycle systems add more; a long-lead construction item |
Wastewater streams
Drain Streams Are Kept Apart Where They Start
Fab drains are segregated at the tool, because mixing incompatible streams, hydrofluoric acid (HF) with alkalis in particular, is hazardous and makes treatment harder. Only the cleanest rinse water goes straight back into the train.
- Reclaimed
- Treated and discharged
- Concentrated or ZLD
| Stream | Contaminants | Treatment | Recycle potential |
|---|---|---|---|
| Rinse water | Trace ions, low TOC | Direct recycle through the polishing train | High: the main source of reuse |
| Acid waste (HF, H2SO4, HCl, HNO3) | Strong acids, fluoride, metal ions | Neutralization; calcium fluoride precipitation | Low |
| Alkaline waste (NH4OH, H2O2, TMAH) | Ammonia, peroxide, developer | Neutralization; ammonia stripping; biological TMAH treatment | Low |
| CMP slurry waste | Silica, ceria, alumina abrasives; Cu, W | Flocculation, filter press, metals precipitation | Very low; solids are hazardous waste |
| Cooling tower blowdown | Concentrated dissolved solids | RO concentration; zero liquid discharge (ZLD) at dry sites | Moderate |
Water and site selection
Water Sets Where Fabs Can Go
Power can arrive on a new transmission line and chemicals by truck, but UPW needs a local source that can supply millions of gallons a day through a drought year.
| Site | Source | Water stress | Strategy |
|---|---|---|---|
| TSMC Arizona, Phoenix | City of Phoenix: mostly reclaimed wastewater, some groundwater | Extreme: Colorado River basin shortage | Fab 1 uses about 4.75 million gallons a day and recycles about 65%; a 15-acre industrial water reclamation plant broke ground in August 2025 and targets 85% to 90% recycling from 2028 |
| TSMC Hsinchu and Tainan, Taiwan | Baoshan and Nanhua reservoirs; reclaimed municipal water | High: seasonal drought | In the 2021 drought reservoirs fell to 5% to 10% of capacity and water was trucked to fabs; reclaimed water plants now supply part of the Southern Taiwan Science Park |
| Samsung Taylor, Texas | EPCOR: Carrizo-Wilcox Aquifer in Milam County via the Sandow Water Project | Moderate: central Texas drought cycles | EPCOR's Blue Sky Water Reclamation Facility treats fab water; the goal is to recycle or reuse about three-quarters of process water |
| Intel Hillsboro, Oregon | Tualatin Valley Water District | Low | Intel reports returning more water than it withdraws at its Oregon sites |
| Intel Ohio One, New Albany, Ohio | Columbus municipal supply; Licking County | Low to moderate | Net-positive water commitment; first fab now expected around 2030 |
| Micron Clay, New York | Onondaga County Water Authority; Oneida Lake | Low | Among the best-watered US fab sites; broke ground January 2026 |
| SMIC Beijing (Yizhuang), China | Beijing municipal supply, partly from the South-to-North Water Diversion | High: one of China's driest major cities | Water strategy not disclosed in detail |
UPW suppliers
UPW System Suppliers
| Supplier | Headquarters | Role | Position |
|---|---|---|---|
| Xylem (Evoqua) | Pittsburgh, Pennsylvania (Xylem bought Evoqua in 2023) | UPW systems; Ionpure EDI; recycle systems | Ionpure EDI is the reference deionization module in US fabs |
| Kurita Water Industries | Tokyo, Japan | UPW design, chemicals, resin management, operations | Strong at Japanese and Taiwanese fabs |
| Organo | Tokyo, Japan | UPW systems and operations | Long-standing supplier to Japanese and Taiwanese fabs |
| Veolia Water Technologies | Paris, France | UPW engineering, wastewater, ZLD, reclaimed water | Strong at European fabs; ZLD for dry US sites |
| Ovivo | Montreal, Canada | UPW integration; CMP and reclaim wastewater systems | Smaller specialist in fab wastewater |
| DuPont Water Solutions | Wilmington, Delaware | FilmTec RO membranes, ion exchange resins, UF | Component supplier to the integrators |
| Toray | Tokyo, Japan | RO and UF membranes, membrane systems | Strong at Korean and Japanese fabs |
| Gaopin Tech | Beijing, China | UPW systems, wastewater reclaim, scrubbers | Domestic Chinese supplier; customers include SMIC |
Resilience
Storage Covers Days, Not Droughts
UPW systems use the same N+1 redundancy as fab power: parallel RO trains, spare deionization vessels and redundant UV, so no single failure stops production. Leading-edge fabs hold one to five days of raw water in tanks or covered reservoirs.
That buffer failed in Taiwan's 2021 drought, when reservoirs serving TSMC Hsinchu and Tainan fell to single-digit percentages of capacity and TSMC trucked in water at more than 2,000 deliveries a day at the peak. Arizona's shortage is structural, not seasonal, so TSMC's Phoenix plan rests on reclaimed water and the reclamation plant instead of storage.
Record
Page Record
- Covers
- UPW purity, the treatment train, use and recycling, wastewater, water at fab sites, suppliers and resilience
- Sources
- City of Phoenix and TSMC reporting (AZFamily, August 2026; DatacenterDynamics, September 2025); EPCOR; Intel and TSMC sustainability reports; SEMI F63; supplier filings
- Last verified
- October 2026