Side stream filtration is a powerful yet often underutilized tool in industrial and commercial cooling water treatment programs. By continuously removing suspended solids from a portion of the system water, side stream filters help reduce fouling, biological growth, scaling, and corrosion—ultimately optimizing cooling system performance and extending equipment life.
At Watertech of America, Inc., we help facilities integrate the right side stream filtration technologies into their cooling water systems to increase reliability, conserve resources, and protect critical infrastructure. This guide outlines the most common side stream filtration options along with their key advantages and considerations.
Why Side Stream Filtration Matters
Cooling towers process large volumes of water, making them vulnerable to contaminant buildup from airborne debris, corrosion byproducts, and biological activity. Without proper filtration, these particulates can accumulate in the system, reducing heat transfer efficiency, damaging equipment, and increasing the risk of microbiological contamination.
Benefits of side stream filtration include:
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Reduced fouling and biofilm formation
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Improved control of scale and corrosion
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Enhanced energy efficiency
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Extended lifespan of heat exchangers, chillers, and pumps
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Reduced maintenance and operating costs
Comparing Side Stream Filtration Technologies
Choosing the right filtration solution depends on the specific conditions of your cooling system, water quality, flow rate, and maintenance resources. Below are common filtration types with an overview of how they work and their pros and cons.
1. Media Filters
How They Work:
Media filters use layered filtration media inside a fiberglass tank to remove particles from the water. Multi-media filters (e.g., sand, gravel, garnet) allow for finer filtration down to 10 microns.
Advantages:
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Highly effective at capturing a broad particle size range
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Automated backwashing for low maintenance
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Customizable media types for specific applications (e.g., iron removal)
Considerations:
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Requires a clean water source for backwash
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High backwash flow rate (up to 5 gpm/sq ft)
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Larger footprint compared to other technologies
2. Cartridge Filters
How They Work:
Water flows through a replaceable filter cartridge, which traps particles larger than its micron rating (often 5–50 microns).
Advantages:
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Low upfront system cost
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Easy to install and operate
Considerations:
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Requires regular cartridge replacements
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Clogged cartridges can cause pressure drops and unfiltered flow
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Higher long-term cost due to consumables and labor
3. Turbo Disc Filters
How They Work:
These filters use compressed stacks of discs made from polypropylene. When a pressure differential is detected, a brief backwash expands and spins the stack to remove trapped solids.
Advantages:
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Compact design ideal for space-constrained areas
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Low backwash water usage (10–12 gallons per cycle)
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Minimal manual maintenance
Considerations:
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Effective down to 50 microns—may not capture fine particulates
4. Centrifugal Separators
How They Work:
These systems use centrifugal force to separate solids from water without screens or filter media.
Advantages:
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No moving parts or consumables
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Extremely low maintenance
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Effective at removing heavy, dense particles
Considerations:
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Limited to particles ≥40 microns
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Best used in combination with other filtration methods
5. Mesh and Weave-Wire Filters
How They Work:
A wire mesh screen traps particles, and when pressure drops, a vacuum cleaning mechanism suctions away contaminants without interrupting system flow.
Advantages:
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Fully automatic and self-cleaning
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Compact footprint
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Low water usage during cleaning
Considerations:
- Less effective at removing organics
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May require occasional manual cleaning
The Right Filtration Delivers Long-Term ROI
Incorporating side stream filtration as part of your cooling water treatment strategy helps protect your investment, reduce water and energy waste, and support compliance with environmental and health regulations—including those related to Legionella prevention.
Watertech: Your Cooling Water Filtration Partner
With over 45 years of water treatment experience, Watertech of America helps facilities evaluate, implement, and maintain side stream filtration systems that are tailored to their specific operations. Our comprehensive programs integrate chemistry, automation, equipment, and on-site support to ensure your cooling system runs clean and efficiently.
Ready to optimize your cooling system?
Contact Watertech today to schedule a site survey.
