Originally published April 11, 2023. Updated October 2026.
Filtration is one of the fundamental processes in a commercial hydroponic water system. The objective is straightforward: remove particles or other unwanted material before they interfere with pumps, valves, treatment equipment, irrigation emitters, sensors, or crop production.
There is no universal filtration train that works for every facility. The correct system depends on the source water, contaminant type and size, required flow rate, downstream equipment, irrigation method, maintenance strategy, and the quality of water required at the point of use.
What Does Water Filtration Do?
Mechanical filtration separates suspended material from water by passing the water through or across a physical barrier. Particles larger than the filter opening are retained while smaller particles and dissolved constituents generally continue downstream.
In commercial hydroponics and greenhouse irrigation systems, filtration may be used to remove:
- Sand and silt
- Plant debris
- Algae and organic material
- Pipe scale and corrosion products
- Precipitates
- Suspended solids from recovered irrigation water
Other water-quality problems may require additional treatment processes. Dissolved salts, alkalinity, hardness, microorganisms, dissolved metals, or specific chemical contaminants cannot always be addressed with conventional mechanical filtration alone.
Start With the Water Quality and the Process
The first question should not be “Which filter should we buy?” It should be “What are we trying to remove, and why?”
A filtration system should be selected around defined operating requirements such as:
- Source-water quality
- Particle size and concentration
- System flow rate
- Available pressure
- Allowable pressure loss
- Irrigation emitter requirements
- Downstream treatment equipment
- Cleaning and backwash requirements
- Water recovery or recirculation strategy
Water testing and analysis can help establish the conditions that should drive filtration and treatment decisions before equipment is selected.
Common Filters Used in Commercial Hydroponics
Screen Filters
Screen filters use a perforated or woven element to retain particles larger than a defined opening. They are commonly used for sediment, sand, pipe debris, scale, and other suspended solids.
Screen filtration is often specified using mesh or micron ratings. A commonly used irrigation filter around 120 mesh corresponds to an opening of approximately 125 to 130 microns, although the exact relationship depends on the screen construction and manufacturer.
Screen filters are simple and compact, but the appropriate design depends on the expected solids loading. Systems with significant organic material may require frequent cleaning unless automatic flushing or another filtration stage is provided.
Disc Filters
Disc filters use stacks of grooved discs that create a three-dimensional filtration path. Suspended material is captured within the grooves as water passes through the element.
Disc filtration can be useful where irrigation water contains a mixture of inorganic particles and organic material. Automatic backwashing configurations are commonly used where continuous operation and reduced manual maintenance are important.
Media Filters
Media filters pass water through a bed of filtration media. They are commonly applied when water contains significant organic loading, algae, or suspended material that may be difficult for a screen filter to manage by itself.
Media filtration is often considered for surface-water sources, recovered irrigation water, and other applications with variable solids loading. Proper sizing and backwashing are critical to maintaining performance.
Cartridge Filters
Cartridge filters use replaceable elements to capture suspended solids at a specified nominal or absolute rating. Depending on the application, cartridges may be pleated, depth-type, melt-blown, wound, or manufactured from other filtration media.
They are useful where fine filtration is required at relatively manageable solids loading. Because cartridges are consumable items, replacement frequency and operating cost should be considered during system design.
Mechanical Filtration vs. Membrane Treatment
Microfiltration, ultrafiltration, nanofiltration, and reverse osmosis are membrane processes with progressively different separation characteristics. They should not automatically be treated as sequential filtration stages.
Microfiltration and Ultrafiltration
Microfiltration and ultrafiltration use membranes to remove increasingly fine suspended and colloidal material. Depending on membrane characteristics, these processes can provide substantial removal of microorganisms and very small particles.
They may be useful when conventional screen, disc, or media filtration cannot achieve the required finished-water quality.
Nanofiltration
Nanofiltration separates some dissolved constituents as well as very small organic compounds. Its ion rejection characteristics differ from reverse osmosis and depend on the membrane chemistry and water conditions.
Reverse Osmosis
Reverse osmosis (RO) uses pressure and a semipermeable membrane to reduce dissolved salts and other constituents in the feedwater. RO is fundamentally different from a conventional irrigation screen or disc filter because its primary purpose is treatment of dissolved contaminants rather than protection from larger suspended particles.
RO systems generally require adequate pretreatment to protect the membranes and maintain reliable operation.
Filtration Is Not the Same as Disinfection
Filtration and disinfection are related but separate water-treatment processes.
Ultraviolet (UV) systems, oxidizing chemicals, ozone, and other disinfection technologies are intended to inactivate or control microorganisms. Activated carbon primarily removes certain dissolved compounds through adsorption. These processes may be used alongside filtration, but they should not be classified as mechanical or membrane filtration.
A commercial water-treatment train may therefore contain several different processes, each selected to accomplish a specific objective.
Protecting Irrigation Equipment
One of the most important functions of filtration is protecting downstream equipment.
Poor filtration can contribute to:
- Clogged drip emitters
- Restricted valves
- Blocked dosing equipment
- Fouled flowmeters and sensors
- Reduced pump reliability
- Membrane fouling
- Increased cleaning requirements
- Uneven irrigation delivery
For precision irrigation, the filtration requirement should be coordinated with the smallest flow passages in the downstream system.
Pressure Loss Matters
Every filter creates resistance to flow. As material accumulates on the filter element, differential pressure across the filter generally increases.
A commercial filtration system should therefore be designed around both clean and dirty operating conditions. Differential-pressure gauges, transmitters, automatic flushing, alarms, or maintenance limits can be used to indicate when cleaning or backwashing is required.
Ignoring filter pressure loss can result in inadequate pressure at irrigation zones even when the pump itself is operating correctly.
Where Should Filtration Be Installed?
Filter location depends on what equipment and processes need protection.
Examples include:
- Source-water filtration before storage or treatment
- Filtration upstream of irrigation distribution pumps
- Fine filtration upstream of irrigation valves and emitters
- Protection upstream of membrane treatment equipment
- Filtration of recovered drain water before storage or reuse
- Dedicated filtration on recirculating process loops
Large facilities may require more than one filtration point because different parts of the water process have different protection requirements.
Select Filtration Around the Complete Water Process
A filter should not be selected in isolation. Source water, storage, pumping, treatment, fertigation, irrigation, drainage, and recovery systems all influence filtration requirements.
Integrated Water Process evaluates filtration as part of the complete water process so that filter type, micron rating, flow capacity, pressure loss, controls, cleaning requirements, and downstream equipment are coordinated from the beginning.
Learn more about our water filters for commercial hydroponics and our approach to hydroponic water testing and analysis.
Need Help With a Filtration System?
Whether you are troubleshooting clogged emitters, evaluating source-water quality, designing a new irrigation system, or upgrading an existing treatment process, Integrated Water Process can help define the filtration requirements before equipment is selected.