Ultrapure water, or UPW, is a high-grade water that’s free from impurities like microbes, minerals, and dissolved gases. It only contains H2O molecules and has a purity level of, or very near, 100%.

Water must undergo a stringent process to become ultra pure and free of any dissolved or suspended organic and inorganic compounds. Ultrapure or highly purified water (HPW) is a term used to show that water has undergone treatment to achieve the highest level of purity. 

UPW is primarily used in the semiconductor and pharmaceutical industries for analytical and manufacturing applications. 

The production of ultrapure water

Ultrapure water is typically produced through the three-stage process summarized below. It requires different levels of purification based on standardized specifications.

1. Pre-treatment stage
   In this stage of a water purification chain, potable water is purified by removing ions through an electro-deionization (EDI) system
2. Primary stage for further purification
   The water then passes through a combined system of reverse osmosis and ultraviolet (UV) light exposure. During reverse osmosis, water passes through a semipermeable membrane that removes large molecules and particles. Meanwhile, the UV treatment involves two wavelengths of UV light, which can kill bacteria and other microbes.
3. Polishing stage
   After the second stage of purification, the deionized water is stored in an inert polyethylene tank. This protects it from contaminants and prevents biofilm from forming. The deionized water then passes through a UV lamp and a polishing cartridge, which removes trace amounts of ions and organic materials. While there’s no perfect system that can guarantee the absolute removal of contaminants, this process makes UPW virtually devoid of contaminants in terms of parts per trillion. In some processing plants, nanotechnology is also used to make UPW.

An ultrapure water system

You can either buy ultrapure water from an online supplier or purchase your own compact ultrapure water system for your laboratory. 

However, you’d need to invest considerably more money if you intend to supply ultrapure water for industrial use. If you do choose this option, the multistaged system can be designed to suit your specifications and target output.

What is the conductivity of ultrapure water?

By definition, ultrapure water contains only H2O molecules and hydrogen and hydroxyl (H+ and OH–) ions in equilibrium. It has a conductivity of 0.055 micro siemens per centimeter (μS/cm) at a temperature of 25˚C.

This makes ultrapure water almost like an insulator compared to copper, which has a conductivity of 58.14 × 106 siemens per meter.

UPW has a resistivity of 18.2 megohms. This, combined with the lack of minerals, makes it dangerous to consume. If you were to drink a glass of UPW, it would strip important electrolytes from your cells. This could prove fatal, as your cells and neural activities are dependent on the right balance of electrolytes to function properly.

Is ultrapure water the same as distilled?

Ultra pure water is not the same as distilled water. The distillation process involves boiling water into vapor form and then condensing it back into the water in a separate container. While this kills bacteria and removes some impurities, however, water produced in this way is not UPW. 

In the illustration above, salt or any substance that’s been dissolved in the water is removed by evaporating the water from the Florence flask. The vapor then passes through the condenser tube, which consists of an interior and exterior tube.

The vapor enters the typically coiled interior tube, while a water coolant passes continuously through the exterior tube. This allows the vapor to cool down and condense in the receiving Erlenmeyer flask. A similar but large-scale process is used in petroleum refining.

Both ultra pure and distilled water have roles in analytical chemistry and clinical-medical diagnosis. Some of these processes include:

• Liquid Chromatography – Mass Spectrometry (LC-MS)
• Gas Chromatography-Mass Spectrometry (GC-MS)
• Graphite Furnace Atomic Absorption Spectroscopy (GFAAS)
• Polymerase chain reaction (PCR)
• Immunochemistry (ICC)
• Mammalian cell culture
• Clinical analyzers
• Trace analysis

Check Out InviPure Systems