A cooling tower loses water two ways: evaporation, which is how it rejects heat, and blowdown, the water drained to keep dissolved minerals from building up. The U.S. Department of Energy sums it up as makeup equals evaporation plus blowdown plus drift (FEMP Best Management Practice 10). Blowdown is the part a site can reduce or recover. This page sets out the main approaches and what each provider says it offers, using each provider’s own published material.
Four approaches
- Run more cycles with better chemistry and controls. Changing the treatment program lets the tower concentrate water further before it bleeds, so it drains less. This recovers no water.
- Treat the makeup water. Removing hardness, silica or salts before they enter the tower raises the cycles the tower can reach.
- Recover blowdown with membranes. Reverse osmosis (RO), often with pretreatment and softening, returns purified water to the tower and leaves a concentrate. Treatment chemicals in blowdown can make RO harder, which is why providers pair it with pretreatment.
- Recover blowdown electrochemically. Ion Concentration Polarization (ICP) uses an electric field and ion-selective membranes to separate dissolved ions while water flows through a low-pressure channel.
Thermal systems and zero liquid discharge sit beyond these, for sites that cannot discharge any liquid. They add energy and solids handling. Our comparison of seven treatment options sets out what each needs and leaves behind, with sources.
What providers publish
The list below is drawn from each company’s own website, case studies or blog, read on 2 November 2026. The order is not a ranking, and the list is not complete.
| Provider | What it publishes for cooling tower blowdown or data center cooling water | Source |
|---|---|---|
| Nalco Water, an Ecolab company | A case study at a colocation data center in Singapore: phosphate-free chemistry to raise cycles of concentration, then “an RO-based water recycling program” to “collect and purify the cooling water blowdown for reuse as cooling tower make-up” | Nalco Water case study |
| Veolia Water Technologies | Data center water programs including chemistry and pH control to cut blowdown, and treated municipal wastewater supplied for cooling | Veolia blog, July 2025 |
| IDE Technologies | Its MAXH2O approach, in which blowdown “is treated using reverse osmosis operated at a conservative local recovery”, with a fluidized bed reactor to remove scaling salts | IDE blog, January 2026 |
| Saltworks Technologies | A blowdown treatment sequence of pretreatment, lower pressure RO, chemical softening and higher pressure RO, with zero liquid discharge “when warranted” (an industrial page, not data center specific) | Saltworks, cooling tower blowdown |
| Genesis Water Technologies | ”Blowdown recovery system design, advanced membrane technologies, and integrated water chemistry programs” for data center cooling | Genesis Water Technologies blog, December 2025 |
| Nona Technologies | Nona RECOVER, a retrofit that applies ICP to cooling tower blowdown and returns treated water to the tower | Nona RECOVER |
How to compare them
The approaches are not exclusive. A site can improve its chemistry and still recover blowdown, and the chemistry program decides how well any recovery system runs. Ask every provider the same questions:
- What share of our blowdown comes back to the tower, measured on water like ours?
- What is left to discharge, how concentrated, and does it meet our sewer limits?
- What pretreatment, chemicals, membranes and power does it need?
- Does it fit our existing tower and treatment program without a shutdown?
Our guide to choosing a recovery system covers these in detail, and how utilities bill water and sewer shows why the same system can pay back quickly in one city and slowly in another.
Where Nona fits
Nona RECOVER treats cooling tower blowdown on site and returns it to the tower, so a site can use up to 50% less water for cooling. It works alongside the existing treatment program and does not recover water lost to evaporation. The savings calculator runs the numbers for a specific tower and local rates.
Sources
- U.S. Department of Energy, Federal Energy Management Program, Best Management Practice 10: Cooling Tower Management
- Nalco Water, an Ecolab company, Global colocation data center improves WUE and reduces greenhouse gas emissions with water reduction, reuse and recycling program
- Veolia Water Technologies, How data centers can solve their water consumption challenge, 23 July 2025
- IDE Technologies, Data centers’ water: turning cooling tower blowdown into a strategic resource, 28 January 2026
- Saltworks Technologies, Cooling tower blowdown
- Genesis Water Technologies, Advanced blowdown treatment technologies for data center water recovery, 18 December 2025