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Deionized Water on Demand

Puretec’s Portable Deionized / Demineralized Water Tank Exchange Service is a safe and economical way to achieve a dependable supply of high purity deionized water.

lon exchange tanks (DI Tanks) remove ionic contaminants that are harmful to many industrial and commercial processes. We offer many different sizes and types of deionized tanks to accommodate various flow and quality requirements.

DI tank exchange service provides deionized water with zero liquid discharge and no chemical handling or maintenance.

Eventually the ion exchange tanks reach exhaustion after a certain amount of use, and this is when Puretec will send a service technician to remove the exhausted tanks onsite and replace them with freshly regenerated tanks.

Our dispatch team is available anytime to schedule tank exchanges for next day deliveries or same day deliveries for emergencies. We also offer remote monitoring solutions as well that provide visibility and proactive notifications to avoid downtime.


All ion exchange resins are regenerated under current Good Manufacturing Practices in compliance with ISO 9001 standards. Only premium ion exchange resins are used to ensure consistent performance and throughput. Each batch of ion exchange resin is tested multiple times throughout the regeneration process for both quality of effluent and throughput capacity.

This guarantees the proper water quality and a predictable run length. For critical laboratory, pharmaceutical, medical and research applications that adhere to USP, CAP/NCCLS/CLSI, ASTM, ISO 3696, GRADE 1-3/TYPE I-IV, and “Milli-Q Water” applications, dedicated and isolated service deionization tanks are available along with full documentation and traceability.

Basics of Ion Exchange

Deionization (also referred to as demineralization) is one of the most efficient processes for removing ionic dissolved salts and minerals from water. Ion exchange is a process where troublesome ions are exchanged for more desirable ions by using specially manufactured ion exchange resins. Ions are dissolved salts or minerals in water that can cause problems in high purity water systems when used as a rinse, coolant or a product ingredient. The purpose of ion exchange is to employ the correct type of ion exchange resins to remove the ionic contaminants that are unacceptable for the customer and replace them with ions that allow the customer to operate without problems. This process provides water that can remove nearly all dissolved salts and gases providing water that is high purity water that is similar to distilled water. The best ion exchange system for you depends on the quality of water entering the system and the quality of water that you require out of the system. By using the proper ion exchange resins it is possible to provide the optimal system for your application. Click the link below to learn more.


Mixed Bed Deionizers consist of Strong Acid Cation and Strong Base Anion ion exchange resins mixed together to produce a higher quality of deionized water with a more neutral pH than dual bed systems. You can expect to see water quality with a resistivity of up to 18.2 Mega-ohms (the highest possible level of deionization/distillation available). Often a dual bed system or RO system will be placed before a mixed bed deionizer, which provides the user with a very reliable high purity source of water. In line conductivity/resistivity meters alert users when the ion exchange tanks need to be replaced with fresh bottles.

A dual bed system consists of (at a minimum) a Cation demineralizer followed by either a Strong Base or Weak Base demineralizer.  A Cation Demineralizer exchanges positively charged ionic contaminants such as calcium, magnesium, iron, manganese, potassium and sodium with the hydrogen (H+) ion.  A Strong Base Anion Demineralizer exchanges negatively charged dissolved ionic contaminants such as chlorides, alkalinity (carbonate and bicarbonates), CO2 gas, sulfates, nitrates and silica for the hydroxyl ion (OH-). A Weak Base Anion Demineralizer removes the above contaminants with the exception of silica and C02.  The resulting stream of water will consist of hydrogen (H+) and hydroxyl (OH-) that together form H20.  Due to the inevitable sodium leakage in a dual bed system, you will not achieve complete deionization. You can expect to see water quality with a resistivity up to 200,000 ohms-cm (2.5 ppm TDS).  A Cation-Strong Base demineralizer will produce a higher than average pH, while a Cation-Weak Base system will produce a lower than average pH.  Additional ion exchange tanks can be added to a dual bed system to achieve desired water quality results. For example, a mixed bed ion exchange tank can be added after a dual bed system to ‘polish’ the water up to 18.2 Mega-ohms resistivity.

Type Resistivity Conductivity TDS pH
Mixed Bed ≤18.2 Ω ≥0.056 µ ≥0 ppm Neutral
Cation-Stong Base Anion ≤200K Ω ≥5 µ ≥2.5 ppm >7
Cation-Weak Base Anion ≤100K Ω ≥10 µ ≥5 ppm <7

GAC removes chlorine and chloramines as well as many dissolved organic contaminants. It does not function on the principles of ion exchange, but a GAC unit is commonly found as part of an ion exchange system or before an RO unit to prevent damage from oxidation or organic fouling.


Once the tanks are installed, they will immediately produce deionized water. Eventually, the DI tanks will become exhausted once the resin beads become saturated with dissolved minerals. When this happens, the water conductivity will drop, and the water quality monitor will signal that it’s time to call Puretec for an exchange. After calling Puretec, or using our online tank ordering feature, a new tank will be delivered the following business day (or same day if an emergency) by one of our drivers who will handle everything. The exhausted tank will be returned to our regeneration facility and prepared for the next time you call.

You need to determine how many gallons of deionized water you need on a daily basis and what quality of deionized water you need. Based on this, we can provide guidance as to what type and size of DI tanks will help you.

This question often arises, yet it lacks a precise answer. Due to the intricate and ever-evolving nature of water chemistry, we can only offer rough estimates. Nonetheless, it’s clear that water with a higher concentration of total dissolved solids (TDS) yields less deionized water, whereas water with a lower TDS concentration produces more.

Additional water quality factors like turbidity and organic content also influence the volume of deionized water generated. Several other aspects can impact the duration of DI system efficiency, including inappropriate flow rates, sporadic operation, bacterial contamination, leaks in bypass valves, the use of downstream copper piping, extreme temperature conditions, air trapped in the system, issues with upstream equipment, and the placement of a 185nm UV system following a mixed bed. Moreover, ensuring that the instruments measuring deionized water quality are correctly calibrated and in good working condition is crucial.