Water Quality Parameters for Liquid Cooling in Data Centers

As data centers continue to grow in scale and power density, liquid cooling has become one of the most efficient strategies to handle rising thermal loads. However, the effectiveness of any liquid cooling system depends not only on the technology itself but also on something often overlooked: the quality of the water circulating through it.

Poor water chemistry can cause corrosion, scaling, fouling, or microbial growth. All of these issues reduce efficiency and risk costly downtime. Maintaining the right water parameters is essential to protect infrastructure and ensure reliable performance.

Why Water Quality Matters

1. Corrosion Prevention: Incorrect pH or high dissolved oxygen accelerates rust and metal degradation.

2. Scaling Control: Minerals like calcium and magnesium form deposits that reduce heat transfer.

3. Biofouling: Bacterial growth creates insulating biofilm layers and can even introduce health risks.

4. Particulate Protection: Dirt, rust, or construction debris can clog cold plates and pumps.

   
   

By carefully monitoring water parameters, operators can extend equipment lifespan, reduce energy use, and secure uptime.

Key Water Parameters for Data Center Liquid Cooling

Parameter	Recommended Range (Typical)	Why It Matters
pH	7.0 – 9.0	Balanced pH minimizes both acid and alkaline corrosion.
Conductivity	50 – 500 µS/cm (system-dependent)	Indicates total dissolved solids; too high promotes scaling, too low increases corrosion risk.
Hardness (Ca & Mg)	< 50 ppm	Limits scaling deposits on heat exchange surfaces.
Chlorides	< 50 ppm	High chlorides accelerate stainless steel corrosion.
Dissolved Oxygen (DO)	< 0.1 ppm	Oxygen is a key driver of corrosion in closed systems.
Iron & Copper	< 0.1 ppm each	High levels suggest active corrosion or contamination.
Microbiological Count	< 10³ CFU/mL (with control program)	Prevents biofilm and pathogens such as Legionella.
Suspended Solids	< 5 ppm	Protects pumps, valves, and cold plates from clogging.

(Note: Exact values should be confirmed with system design guidelines, ASHRAE TC 9.9 recommendations, and local regulations.)

Best Practices for Water Treatment

• Filtration: Use multi-stage filters to remove solids and construction debris.

• Chemical Treatment: Apply corrosion inhibitors, scale suppressants, and biocides tailored to system design.

• Regular Monitoring: Implement automated sensors for pH, conductivity, and temperature. Conduct routine lab analysis for metals and microbiological content.

• Flushing and Cleaning: Schedule pre-commissioning and periodic flushing to remove sediment and biofilm.

  
  

Conclusion

Water quality is not just a maintenance detail—it is the foundation of a reliable liquid cooling strategy in modern data centers. By controlling key parameters and implementing a proactive water treatment program, operators can secure uptime, optimize thermal efficiency, and protect their investment in high-value infrastructure.

In summary, understanding the importance of water quality and adhering to best practices can significantly enhance the performance of liquid cooling systems. It is crucial to prioritize these aspects to ensure the longevity and efficiency of data center operations.