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Closed Loop Water Systems

What is a Closed Loop Water System?

When hot or chilled water recirculates through a piping system with little to no makeup water it is known as a closed loop. Some of the concerns with closed loop systems are corrosion, scale, particulate and microbiological growth. Closed loop systems maintain water volume and quality; typically experiencing losses of less than 10% of its total volume annually. 

It is important to maintain high quality water within a closed loop system. Ignoring water treatment in these systems can be a costly mistake. To ensure a system is well maintained and operating at peak efficiency it needs to be treated with the right chemicals to fit your metallurgy restrictions and manufacturer’s specifications. Making sure your inhibitor residuals, conductivity, pH, metals, and bacteria counts are in range is extremely critical. 

Watertech offers a range of solutions for closed loops:

Closed Loop Scale and Corrosion Inhibitors

Watertech has specifically formulated inhibitors that help protect closed loops from corrosion and scale formation. As fresh water is added to the loop, oxygen is introduced. When left untreated, this can quickly cause pitting and corrosion. 

Closed Loop Biocides

Watertech offers a range of biocides used to prevent fouling and microbiological growth specifically for closed loops. These help to prevent build-up of biofilms on pipe surfaces and microbial induced corrosion like iron reducing, denitrifying, and sulfate reducing bacterium. 

Closed Loop Freeze Protection- Glycols

Freezing conditions can cause challenges for industrial and commercial applications. Watertech recommends using inhibited glycol as a frost protection chemical for systems that are vulnerable to the effects of freezing temperatures. Propylene and ethylene glycol can be ordered in a range of concentrations, inhibitor packages, and containers that can be formulated depending on your application. 


Including a filtration system to your closed loop can help remove suspended solids and particulate, which can potentially cause long term damage to the piping and process equipment. This is typically achieved through side-stream filtration. Removing suspended solids improves efficiency and helps prevent equipment damage. 

Closed loops should be checked regularly for leaks and water treatment parameters. If you have questions about your hot or chilled water loops, or are looking to purchase glycol please fill out our site survey and we would be happy to help.

Watertech is a resource for all of your water related needs. 

Please reach out with questions about your system or request a site survey.

Each facility is unique. The best way to address your needs is by conducting a site visit. Please click the link below, fill out the form and one of our Technical Engineers will be in touch.