Why Do Some Companies Insist You Purchase DI Water Directly From Them?

The simple answer is profit.

Read the manual supplied by the manufacture of your system. Some manuals may say to use only DI Water in the cooling system. The reason being is that the cooling water passes over the high voltage contacts on both ends of the stimulation lamp while the unit is firing and therefore must be as non-conducting (resistive to electrical current) as possible.

How do lasers use this water in the first place?

All low powered pulsed lamp micro welders regardless of their manufacture, use a closed loop water-to-air heat exchanger to keep the laser cool during operation.

Water flows over the laser rod then the laser lamp where it removes the built up heat and delivers it to a cooling coil - where a fan blows room temperature air across the cooling coil. The difference between the water circulating over the laser rod and the heat pumped out through the cooling coils into the room can be as great as 20 degrees F.

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Once the water is thoroughly circulated through a fresh DI Filter Cartridge, the ion-exchange resins in the cartridge bring the water to the correct resistivity which is now compatible for use with the laser welding system.

Since all use water as a coolant why do some companies insist that you purchase water directly from them?

Water is a profit source for those companies. It is not uncommon to see charges as high as $10.00 per gallon. Add on handling and shipping the charges to the customer can exceed $35.00 per gallon.

But are you really buying DI Water?

Not exactly according to the definition of what constitutes DI Water.

If you bought DI water from the laser welder vendor, then what you probably bought is partially filtered tap water with a resistivity of somewhere between .3 and .9 mega ohms when measured with a simple hand held multi-meter.

Labeled as “DI Water”. It is typically sourced from city tap water and run through a DI filter before being placed into a one gallon plastic jug. This is the very same type of DI filter that is already on the pulsed lamp micro welders.

Tap water is full of ions from the soil (Na+, Ca2+), from the pipes (Fe2+, Cu2+), and other sources.

Real DI water is usually deionized by using an ion exchange process.

For more information on the processing of DI water and the differences in distilled and purified water follow these links:



What is the advantage or disadvantage of the $10.00 per gallon filtered water?

  • At the best, it probably extends the life of the light duty DI filter cartridge installed in your laser welder by several weeks.

  • At the worst, it is slightly better than pouring tap water into your laser welder. In some cases, when the laser is not used regularly a white or yellowish mineral scale develops on the reflective surfaces in the laser cavity which requires cleaning.

  • Important Note: Before considering using any alternative water or coolants consult with the manufacture of your laser system for their “terms of warranty”.

Is there an alternative to purchasing $10.00 per gallon filtered water?

Yes, use locally sourced “steam distilled” water. Steam distilled water is available in most grocery stores. “Steam distilled” means getting the purest water available.

Steam Distilled water, is water, which has been heated to the boiling point, into vapor or steam. At that point impurities are separated from the water which is then condensed back into pure liquid form. Steam Distilled water contains no solids, minerals or trace elements and has no taste.

Reflecting our years of industrial experience, American Laser Welding uses heavy duty DI water filters that efficiently take off-the-shelf steam distilled water and brings it to the proper resistivity.

Selecting a laser welding vendor that offers robust equipment industrial laser systems makes a big deference in both the uptime and the cost associated with routine maintenance.