Cooling tower blowdown is necessary because

LEED v4.1 O+M Reference Guide, p.1132: LEED v4 - U.S.Green Building Council(https://www.usgbc.org/guide/om) 3: What is Blowdown Loss in Cooling Towers?(https://deltacooling.com/resources/faqs/what-is-blowdown-loss-in-cooling-towers).

Cooling tower blowdown is a process used to manage water quality in cooling systems. It involves discharging a portion of the water from the system to control the concentration of dissolved solids and minerals, which accumulate due to the continuous evaporation of water. These dissolved solids can increase the water's conductivity, leading to scale formation, corrosion, and biofouling, all of which can significantly decrease the efficiency and lifespan of the cooling system. By performing blowdown, the system maintains the water quality within acceptable limits, ensuring optimal performance and energy efficiency of the cooling tower.

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The need for cooling tower blowdown due to the accumulation of dissolved solids is discussed within the context of water management practices in cooling systems in the LEED AP O+M documentation. This process is crucial for maintaining system efficiency and is covered under the Water Efficiency category, emphasizing the importance of water management in achieving sustainable building operations.