Water > Cooling Towers

Cooling towers help to regulate building temperature by cooling circulating water that is used in chillers, air-conditioning equipment, or other process equipment. The cooling tower rejects heat and cools the water primarily through water evaporation, meaning that cooling towers consume significant amounts of water.

There are several ways to improve the water efficiency of the cooling towers at your sports facilities. Please review the sections and Additional Resources below for more advice. Contact facilities staff to discuss strategies that apply to your sports venue cooling tower infrastructure.


Whenever possible, choose a closed-loop cooling tower, which can save hundreds of gallons of water per day on average by reducing evaporation. In addition, investigate whether your area allows the use of non-chemical cooling towers and water conditioning systems. These use polarization technology or sand filtration combined with ozone for disinfection instead of chemicals, helping keep polluted discharge out of the sewer system, and lower water consumption by reducing the need for make-up water.

The U.S. Department of Energy provides detailed recommendations for water-efficient operations and maintenance of cooling towers, including the following. The full list of recommendations is available at U.S. Department of Energy.

  • Calculate and maximize “cycles of concentration.” Many systems operate at two to four cycles of concentration, while six cycles or more may be possible. Increasing cycles from three to six reduces cooling tower make-up water by 20% and cooling tower blowdown by 50%.

  • Install a conductivity controller to automatically control blowdown. A conductivity controller can continuously measure the conductivity of the cooling tower water and discharge water only when the conductivity set point is exceeded.

  • Install flow meters on make-up and blowdown lines.

  • Consider using acid treatment such as sulfuric, hydrochloric, or ascorbic acid where appropriate. When added to recirculating water, acid can improve the efficiency of a cooling system by controlling the scale buildup potential from mineral deposits.

  • Select your water treatment vendor with care. Tell vendors that water efficiency is a high priority and ask them to estimate the quantities and costs of treatment chemicals, volumes of blowdown water, and the expected cycles of concentration ratio. Keep in mind that some vendors may be reluctant to improve water efficiency because it means the facility will purchase fewer chemicals. In some cases, saving on chemicals can outweigh the savings on water costs. Vendors should be selected based on “cost to treat 1,000 gallons make-up water” and highest “recommended system water cycle of concentration.” Treatment programs should include routine checks of cooling system chemistry.


There are a variety of retrofit options available to help maintain water efficiency across cooling towers at your sports facilities. The U.S. Department of Energy provides a detailed list of retrofit strategies, including the following:

  • Install a sidestream filtration system composed of a rapid sand filter or high-efficiency cartridge filter to cleanse the water. This enables the system to operate more efficiently with less water and chemicals.

  • Install a make-up water or sidestream softening system when hardness (calcium and magnesium) is the limiting factor on cycles of concentration. Water softening removes hardness using an ion exchange resin and can allow you to operate at higher cycles of concentration.

  • Install covers to block sunlight penetration. Reducing the amount of sunlight on tower surfaces can significantly reduce biological growth such as algae.

  • Consider alternative water treatment options, such as ozonation or ionization, to reduce water and chemical usage. Be careful to consider the life-cycle cost impact of such systems.

  • Install automated chemical feed systems on large cooling tower systems (over 100 tons). The automated feed system should control blowdown/bleed-off by conductivity and then add chemicals based on make-up water flow. These systems minimize water and chemical use while optimizing control against scale, corrosion, and biological growth.


Improving water efficiency measures for the cooling towers at your sports facilities can help your institution earn points within the “Water” subcategory of AASHE’s Sustainability Tracking, Assessment & Rating System (STARS). It can directly contribute to earning up to 6 points for the credit “OP 26: Water Use.” Work with sustainability and facilities staff on your campus to support any institutional efforts to attain or improve your institution’s STARS rating. Use the STARS 2.0 Technical Manual to learn more.


Almost half the world’s population lives without a reliable supply of clean drinking water. In the United States, many sources of freshwater are being depleted faster than they can be recharged by natural processes. This is especially true in the Southwest. The Colorado River, for example, which supplies water to 30 million people in seven states and Mexico, is at its lowest level since water flow records began being kept about 100 years ago. It often runs dry before it reaches the sea, adversely impacting farmers, residents, and aquatic life.

Water conservation is especially important in light of the looming pressures of global warming, which threaten to significantly increase evaporation as well as instances of severe drought. Water scarcity will rival sea level rise as one of the most threatening consequences of global climate disruption for communities across the United States and worldwide. Water conservation measures can help to ensure that current and future generations have access to the water they need.


NRDC – Water
AASHE Sustainability Tracking, Assessment & Rating System (STARS)
AASHE STARS 2.0 Technical Manual
U.S. Department of Energy: Cooling Towers: Understanding Key Components of Cooling Towers and How to Improve Water Efficiency
LEED: Cooling Tower Water Management
Office of Energy Efficiency and Renewable Energy: Cooling Tower Management
California Institute of Technology Case Study: Increasing Cooling Tower Water Efficiency
FEMP Water Efficiency
Cooling Technology Institute
American Society of Heating, Refrigeration, and Air-Conditioning Engineers
American Society of Mechanical  Engineers
U.S. Environmental Protection Agency WaterSense at Work: Cooling Towers (includes information about efficient technology and operational improvements to save water in cooling towers)
Side Stream Filtration for Cooling Towers Fact Sheet
Office of Energy Efficiency and Renewable Energy: Guide to Understanding Key Components of Cooling Towers and How to Improve Water Efficiency
Cooling Technology Institute