The Water Problem at Oyu Tolgoi: Mining in the Gobi Desert

The Oyu Tolgoi mine, in Mongolia’s South Gobi Desert, holds one of the biggest gold and copper deposits ever found. It’s such a huge project that it attracted investment from Rio Tinto and the Mongolian government. Fluor Corporation, one of the world’s largest engineering and construction companies, stepped in to manage its development.

But the Gobi Desert is one of the toughest places on Earth for a lot of people to live. It gets less than 200 millimeters of rain a year. There’s basically no surface water for hundreds of kilometers between the mine and the closest towns. The groundwater you do find under the Gobi? It’s mostly brackish, meaning it’s packed with dissolved salts, minerals, and in some spots, arsenic and fluoride. These levels are way higher than what the WHO says is safe for drinking water.

A mining camp housing 40,000 employees, who live there for three-month shifts, needs roughly 2–4 million gallons of drinking water every day for everything. That includes drinking, cooking, sanitation, medical facilities, fire suppression, and even keeping dust down on roads and processing areas. The only real solution was industrial-scale water purification. They needed technology that could turn that brackish groundwater into water meeting WHO drinking standards. And it had to be reliable, because 40,000 people’s daily survival depended on it.

Why They Chose Industrial Reverse Osmosis

Fluor Construction looked at a lot of different water supply technologies for Oyu Tolgoi before they picked reverse osmosis. What were they looking for? The system needed to handle brackish groundwater with varying and potentially high TDS. It had to be proven reliable in remote places with little maintenance help. It needed to scale up for different phases of camp growth, have a modular design for easy installation in the desert without special construction gear, and offer a good operating cost per cubic meter of water produced.

Reverse osmosis was the clear winner. Unlike thermal desalination, which needs a lot of heat energy (tough to supply efficiently in a remote spot), RO systems run on electricity. The mine’s on-site power infrastructure could handle that. And unlike chemical treatment, RO makes water that meets drinking standards even when the source water chemistry changes. That’s a huge plus when you’re dealing with desert aquifers that can vary a lot across the extraction area.

AMPAC USA was chosen to supply two industrial RO plants for the project. Each unit produces 80,000 GPD (gallons per day), which is about 12.7 cubic meters per hour, or 302 cubic meters daily. Together, these two units make 160,000 GPD, roughly 600 cubic meters of drinking water every day. That was enough to supply the initial camp population before they added more capacity later.

Technical Specs: Industrial RO for Desert Mining

The industrial reverse osmosis plants we sent to Oyu Tolgoi were built specifically for the Gobi Desert’s harsh conditions. Standard commercial RO systems, made for mild climates and treated city water, would quickly fail there. AMPAC USA designed these systems from the ground up to handle the unique challenges of this location.

What Was in the Source Water

Gobi Desert groundwater is tough stuff to treat. Total dissolved solids (TDS) in desert aquifer water usually range from 1,000 to 5,000 mg/L, or even higher. That’s classified as brackish water. The specific mix of ions includes high levels of sulfates, chlorides, and in some Mongolian aquifer zones, fluoride and arsenic. These need extra treatment steps beyond standard RO. Before we designed the system, AMPAC USA did a full water quality analysis. We looked at TDS, pH, hardness, alkalinity, sulfate, chloride, nitrate, iron, manganese, silica, arsenic, and fluoride to make sure our pre-treatment was right and the final water met WHO standards for everything.

Pre-Treatment System

The pre-treatment for the Oyu Tolgoi systems protected the RO membranes from the high fouling potential of desert groundwater. It included multi-media depth filtration to remove suspended solids and fine particles. We added activated carbon adsorption to get rid of organic compounds and oxidizing agents that could hurt the membrane polymer. There were also anti-scalant chemical dosing systems to stop minerals from building up at higher concentrations, and in-line cartridge filtration as a final guard right before the high-pressure pump.

High-Pressure RO Membrane Stage

The AMPAC USA industrial reverse osmosis systems use brackish water RO membranes that run at 150–300 psi (10–21 bar). That’s perfect for the TDS range of Gobi aquifer water. Each 80,000 GPD unit has multiple pressure vessels arranged side-by-side, and each vessel holds 6–7 spiral-wound membrane elements. The system gets a recovery rate of 70–75%. That means 70–75% of the source water becomes product water, and only 25–30% is discharged as concentrated brine. We optimized this recovery rate for the available groundwater and the need to manage brine disposal in a desert.

Desert-Specific Design Features

Running a water purification system in the Gobi Desert needs design choices you just don’t think about in mild, developed areas:

• Extreme temperature tolerance: Gobi Desert temperatures swing from -40°C in winter to +40°C in summer. We designed the systems with insulation, heat tracing for exposed pipes and membrane elements, and cooling features to keep them at the right operating temperature all year.
• Sand and dust protection: Mining operations kick up a lot of airborne particles. These would quickly clog open electrical and mechanical parts. All enclosures are rated IP65 or higher, and air intakes for electrical panels use coarse filters to keep out fine sand.
• Simple maintenance: There aren’t special water treatment technicians on site, and the closest major repair shop is hundreds of kilometers away. So, we designed the systems for camp maintenance crews with basic mechanical skills to operate and do routine upkeep.
• Spare parts: AMPAC USA sent a full initial inventory of spare parts, enough for 24 months of operation. This let the mine keep the systems running without relying on supply chains for everyday consumables.
• Modular transport and installation: We designed the systems to fit in standard shipping containers. They could be installed without heavy construction equipment, using the mine’s own vehicle fleet for lifting and placement.

The Scale of the Challenge: Water for 40,000 People in the Desert

Forty thousand people living on site, with a full workforce always present, is like a small city. Meeting their water needs in a place with no natural fresh water is a huge engineering task. It demands industrial-grade reliability and backup systems.

Here’s a typical breakdown of water use for a big mining camp:

• Drinking water: At least 4–5 liters per person per day; the WHO recommends 10 liters for good hydration in hot, physically demanding work.
• Food prep and cooking: 3–5 liters per person per day.
• Personal hygiene (handwashing, bathing): 15–30 liters per person per day.
• Medical and sanitation: 50–100 liters per person per day in well-equipped camp medical facilities.
• Laundry: 10–15 liters per person per day for washing clothes and linens.

The WHO suggests a minimum of 50 liters per person per day for all personal and household uses in temporary settlements. For 40,000 workers, that’s at least 2 million liters (about 530,000 gallons) of drinking quality water every day just for personal use and hygiene. And that doesn’t even count water for industrial processes, dust suppression, or fire protection systems.

Industrial Water Treatment for Mining and Resource Extraction

The Oyu Tolgoi project is a great example of a problem mining operations everywhere face: getting safe water to huge, remote workforces when natural fresh water isn’t there or isn’t enough. Global Water Intelligence says the mining sector used about 9–10 billion cubic meters of water globally in recent years. That’s more than several medium-sized countries use in an entire year.

Water management at mines increasingly involves a full cycle of treating, reusing, and recycling water. AMPAC USA’s industrial water treatment systems help with many parts of this cycle:

• Feed water purification: Converting brackish groundwater, river water, or process water to potable or process-grade quality
• Process water treatment: Providing specific water quality parameters for mineral processing, flotation, and hydrometallurgical operations
• Produced water treatment: Processing mine drainage, tailings pond water, and acid mine drainage (AMD) for reuse or safe discharge
• Zero liquid discharge (ZLD): Treating brine concentrate to minimize or eliminate liquid discharge in environmentally sensitive desert environments

AMPAC USA Capabilities in Remote Industrial Water Supply

AMPAC USA has been supplying industrial water treatment systems to remote and demanding environments since 1989. Our systems have been deployed in deserts, Arctic environments, remote Pacific islands, offshore oil platforms, and military forward operating bases — wherever reliable, high-quality water production is needed far from municipal supply infrastructure.

All AMPAC USA systems are manufactured under ISO 9001:2015 quality management systems and are designed to NSF/ANSI 58 standards where drinking water applications require certification. Our engineering team provides comprehensive project support from initial water quality analysis through system design, factory testing, delivery, commissioning, and long-term service support.

For large-scale industrial water supply projects, AMPAC USA works directly with EPC contractors like Fluor Corporation, as well as with mine owners, government agencies, and development finance institutions. Our experience with international logistics, remote installation, and multi-year service contracts makes us a reliable partner for projects in any location on earth.

Explore our industrial water treatment capabilities, learn about our brackish water treatment systems, or visit our water treatment systems page for specifications. To discuss a remote or industrial water supply project, contact our engineering team. Read more about AMPAC USA’s history and global deployments on our company page, or explore more project case studies on our blog.

Step-by-Step: How AMPAC USA Approaches Remote Industrial Water Projects

1. Water quality analysis: Comprehensive testing of all available water sources — groundwater, surface water, recycled process water — to characterize feed water chemistry and identify contaminants requiring treatment.
2. Process design: Selection of pre-treatment, primary treatment (RO, NF, UF), post-treatment, and disinfection stages based on feed water characteristics and product water requirements.
3. System sizing: Capacity calculation based on population, consumption standards, storage requirements, and production schedule, including redundancy factor for maintenance periods.
4. Engineering and documentation: Complete P&ID, equipment datasheets, civil/structural requirements, electrical single-line diagrams, and instrumentation diagrams for integration with site construction plans.
5. Manufacturing and factory acceptance testing: Systems are manufactured in AMPAC USA’s production facility, fully assembled and tested against water quality specifications before shipment.
6. Logistics and installation support: AMPAC USA coordinates shipping to remote sites, provides installation supervision, and commissions systems to operational readiness.
7. Training and handover: Site personnel receive comprehensive training on operation, routine maintenance, and troubleshooting before AMPAC USA’s commissioning team demobilizes.
8. Ongoing service support: Remote diagnostics, planned maintenance visits, and spare parts programs maintain system performance through the project’s operational life.

Frequently Asked Questions: Industrial RO Water Treatment for Mining and Remote Sites

What is the capacity of the AMPAC USA systems at Oyu Tolgoi?

AMPAC USA supplied two industrial reverse osmosis water purification plants to the Oyu Tolgoi mine, each with a production capacity of 80,000 gallons per day (GPD), equivalent to approximately 12.7 cubic meters per hour or 302 cubic meters per day. The combined output of the two systems is 160,000 GPD — approximately 600 cubic meters per day of potable water. This production capacity was sized to serve the initial phases of camp development, with additional capacity planned as the mine population grew. AMPAC USA’s industrial RO systems are available in production capacities from 10,000 GPD to well over 1,000,000 GPD in a single skid-mounted configuration, with multiple skids available for larger requirements. See our reverse osmosis systems page for current capacity specifications.

What is brackish water and why does it need special treatment?

Brackish water is water with salinity between fresh water (below 500 mg/L TDS) and seawater (approximately 35,000 mg/L TDS), typically ranging from 1,000 to 15,000 mg/L TDS. Brackish groundwater is common in arid and semi-arid regions where evaporation concentrates dissolved minerals in the soil and aquifer. Brackish water cannot be consumed without treatment — at TDS levels above 1,000 mg/L, drinking water tastes unpleasant and at higher levels can cause dehydration by drawing water out of cells rather than hydrating them. Conventional treatment (coagulation, flocculation, filtration) does not remove dissolved salts. Reverse osmosis is the primary technology for brackish water desalination, using semi-permeable membranes to separate fresh water from the dissolved salts under pressure. AMPAC USA’s brackish water treatment systems are designed specifically for the TDS range and water chemistry of the application.

How reliable are industrial RO systems in extreme desert climates?

Modern industrial RO systems, when properly designed for the specific environmental conditions, achieve extremely high reliability — typically above 95% availability on an annual basis. The key design considerations for desert deployment are: thermal management (insulation and heat tracing for cold winters; shading and ventilation for summer heat), dust and sand exclusion (IP-rated enclosures and filtered air intakes), conservative flux rates that avoid overloading membranes and driving premature fouling, and adequate pre-treatment to protect membrane life. AMPAC USA has extensive experience with desert and extreme climate deployments across the Middle East, Africa, Central Asia, and South America. Our systems are designed with local climatic data as a primary design input, not an afterthought. Properly maintained, industrial RO systems in well-designed enclosures routinely achieve 10–15 year operational lifespans before major component refurbishment.

How is brine disposal managed at a remote desert mine site?

Brine disposal is one of the critical environmental engineering challenges at remote desert water treatment installations. At a recovery rate of 70–75%, the Oyu Tolgoi systems generate approximately 25–30% of their feed water volume as brine concentrate — for a combined 160,000 GPD production system drawing 220,000 GPD of feed water, this means approximately 55,000–65,000 GPD of brine requiring disposal. Options include deep well injection (where suitable geology exists), evaporation ponds (effective in desert climates with high evaporation rates), brine concentration and zero-liquid-discharge (ZLD) evaporators for minimal environmental footprint, and in some cases, industrial use of the brine stream as process water for certain mining operations. The Mongolian regulatory framework and the site’s specific geology and climate informed the disposal approach selected for Oyu Tolgoi. AMPAC USA’s system design accounts for brine management as an integral part of the water treatment solution, not a residual problem.

Can AMPAC USA supply systems for mining projects in other remote locations?

Yes. AMPAC USA has supplied water treatment systems to remote mining and resource extraction projects across more than 40 countries since 1989. Our project portfolio includes mine water supply systems in desert, arctic, tropical, and high-altitude environments — anywhere human workers need safe water and municipal infrastructure does not exist. We work with EPC contractors, mine owners directly, government mining authorities, and development finance institutions. AMPAC USA can provide systems in any production capacity required, designed for the specific feed water chemistry, climate, and logistical constraints of the project location. We have experience with both permanent mine infrastructure and temporary camp installations that need to be demobilized and redeployed as mine operations move. Contact our engineering team with your project location, population requirement, and source water information to begin the design process.

What water quality standards do the systems produce?

AMPAC USA industrial RO systems are designed to produce water meeting World Health Organization (WHO) Guidelines for Drinking Water Quality, which specify maximum limits for all major chemical, microbiological, and physical parameters. The WHO limit for total dissolved solids (TDS) in drinking water is 600 mg/L (with 1,000 mg/L as an acceptable upper limit in some circumstances). AMPAC USA systems consistently produce water with TDS below 500 mg/L — typically 50–200 mg/L depending on the feed water chemistry and recovery rate — well within WHO standards. Beyond TDS, the systems are designed to meet WHO limits for all specific contaminants present in the feed water, including arsenic, fluoride, nitrates, and any other site-specific parameters identified in the feed water analysis. Post-treatment disinfection ensures microbiological compliance. All systems are factory-tested before delivery and performance-tested at commissioning against the agreed water quality specification.

How does AMPAC USA compare to other industrial water treatment suppliers?

AMPAC USA differentiates itself in industrial water supply projects through its combination of engineering depth, manufacturing control, and international operational experience. Unlike equipment brokers or distributors who specify standard packaged systems, AMPAC USA designs and manufactures systems to the specific requirements of each project — including challenging feed water chemistries, extreme operating environments, and unusual logistical constraints. Our ISO 9001:2015 certified manufacturing ensures consistent quality across all systems. Our 35+ year track record in demanding international environments — including US military contracts — provides evidence of performance under the most rigorous conditions. And our full project lifecycle support, from initial water analysis through commissioning and long-term service, provides a single point of accountability for complex projects like Oyu Tolgoi. Learn more about AMPAC USA or contact us to discuss your industrial water supply requirement.