Mechanical Insights

How Do I Empty Cooling Towers

Oct 4, 2021 8:30:00 AM / by Tate Engineering

tate cooling towers

Everyone knows that air filters need to be changed in your HVAC system, but what about your cooling towers? Cooling towers often run around the clock - and all year long. They have to be emptied and cleaned to keep particulates and bacteria from building up and causing problems.  Clean cooling tower water is good for everybody.

Why Do Cooling Towers Need to Be Emptied?

Water usually isn’t just pure water. Water that comes out of the tap has minerals and other compounds dissolved within it. While this isn’t normally a problem, when the water evaporates, these minerals are left behind. As the concentration of these minerals increases in the cooling tower water, these particulates can gunk up parts of the cooling tower and reduce the cooling tower’s efficiency.

In addition to minerals and particulates, bacteria can be a big problem for cooling towers. As air passes through a cooling tower, the water acts like a filter. Particles from the air, including bacteria, are pulled out and deposited into the cooling tower basin. Over time, the level of bacteria grows in the cooling tower water.

Without routine cleaning, the bottom of a cooling tower will build up a layer of sludge, minerals, and bacteria. Keeping this layer at a minimum is crucial to keeping your facility’s cooling system operational. Removing all of the gunk from the cooling tower is much easier than trying to clean chiller tubes and other components.

How to Clean a Cooling Tower

Safety is paramount when cleaning cooling towers. Before beginning any cleaning operation, be sure to use the correct PPE. Cleaning your cooling tower often involves multiple steps. To kill bacteria and algae, add a biocide directly to the cooling tower water prior to additional cleaning. Be sure to follow the biocide manufacturer’s recommendations, which often include waiting a few days before continuing the cleaning process.

Whenever visible buildup has occurred in the cooling tower basin, cleaning needs to happen. To prevent excessive buildup, have cooling tower cleaning on a preventative maintenance schedule. Cleaning the cooling tower once a month is often sufficient to keep the system operational and effective, but cleaning should certainly happen more often if needed. To clean your system, you have two main options: vacuuming and a bleed-off.

Related: How Do I Start Preventative Maintenance?


Vacuuming a cooling tower is similar to cleaning a swimming pool. To prevent draining the entire system (and keep the cooling tower online), a vacuum and hose system is used to suck out all of the gunk from the cooling tower basin. The muck and water is then either flushed away or run through a reclaim system where the water is filtered before being returned to the basin. Vacuuming can be done routinely or as needed to keep the cooling tower clean. Be sure to top off water levels after vacuuming.


During a bleed-off, the cooling tower’s water is drained and the water level is either allowed to fall so more intense cleaning can occur, or the fouled water is replaced with fresh water as the system is drained so that the cooling tower stays operational. Depending on your facility, and the type of cooling tower you have, a permit from the NPDES may be required before draining.

As the water level is drained, any fouling or scale buildup should be removed. If the fouling is excessive, use a foaming detergent to cut through the muck and eat away at deposits. Rinse and clean the system thoroughly after using a detergent. Doing a bleed-off at least twice a year is a good way to keep your cooling tower safe and efficient.

No matter which cleaning method you use, ensure that the water levels are correct before finishing the job. Adding conditioners to your cooling tower water can help to minimize scale and other buildup for the next time you clean.

Cooling tower cleaning may seem intimidating, but it doesn’t have to be. Having a plan and a schedule can take the complexity out of it. Keep your cooling towers operating just right with thorough, routine cleaning. Reach out to the experts at Tate for any of your cooling tower questions.

Contact Us

Tags: Seasonal, Equipment

Written by Tate Engineering