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Pressure Filters


Pressure Filter for effluent wastewater pump
  • Protects pressurized systems from costly repairs

  • Lowers total suspended solids (TSS)

  • Keeps distribution holes free of debris & extends drain field life

  • Protects without high head-loss, only .21 psi (about half a foot)

  • Easy to service, a five minute job from start to finish

  • Easy to install

  • Low maintenance due to vortex scrubbing action and open area

  • Last line of defense, protecting no matter where solids are introduced

  • Can be used in a manifold configuration to handle almost any flow-rate

  • Multiple filtration sizes available - from .004" to .125"

Just a few benifits of the pressure filter

Made in the USA

How the Sim/Tech Pressure Filter Works

The Sim/Tech pressure filter is extremely effective in providing protection for all pressurized distribution  systems.  If you need to protect a pressurized system from suspended solids, the pressure filter can perform the job.  Most pressurized wastewater distribution systems such as mound systems are very effective in treating effluent. In pressurized systems the effluent or gray water is pumped from the holding or pump chamber of the septic system out to the drain field by a low pressure effluent pump. The drain field is where the problems show up. The lateral piping in the drain field has many small holes to drain the effluent. These holes can be as small as 1/8", as you might imagine it doesn't take a lot of contaminants to plug the drain holes. With each hole that becomes plugged the efficiency of the pressure distribution system falls, until the system eventually fails.  Many of these systems only partially fail over a long period of time, causing contamination of ground water long before the system shows any visible signs of distress.  Placing an effluent filter just before entering the forced main of the pressurized septic system is an extremely effective solution. The pressure filter is mounted onto the discharge port of any effluent pump, thereby, filtering out contaminants before they enter the distribution system or drain field.  The SIM/TECH STF-100A2 effluent filter has been designed to assure that the small holes in the distribution piping remain unclogged. The filter system is unique to the industry, engineered to provide maximum protection for your sanitary pressure system.

Hair, dirt, seeds, fruit & vegetable skins and more that was filtered out by the pressure filter

dirty pressure filter screen from septic system
example of dirty pressure filter screen
dirty pressure filer screen from septic system
dirty pressure screen from septic system
dirty pressure filter screen from pressurized septic system

Hair, dirt etc. clogging discharge holes on systems that were not protected by the pressure filter

clogged discharge hole on sand mound septic system field piping
clogged hole from pressure onsite wastewater system


Because the pressure filter is installed on the pressure side of the effluent pump, it is difficult for the internal filter mechanism to become clogged. The inherent design of effluent pumps create an on-and-off scrubbing action caused by shock waves as the effluent pump works. This scrubbing action is strongest near the pump, this is why the filter is attached directly to the pressure side of the effluent pump.  The high flow rates and low pressure loss of the pressure filter are achieved by a large filter area with over 40% of the filter screen being open. The pressure filter handles flows over 80 gallons per minute, so even a partially contaminated wastewater filter will keep virtually any pressurized distribution system functioning properly.

pressure filter cutaway showing vortex action

Ease of Use

The picture above illustrates the vortex scrubbing action associated with the mounting location of the filter.

The pressure filter assembly is installed and serviced in a matter of minutes, making this product unique to the industry. The pressure filter easily threads onto the discharge port of any effluent pump.  On the occasion when a filter does need cleaning, it can be removed easily, washed clean of debris and contaminants then reinstalled in the pressure filter assembly. The entire process takes only minutes.

The pressure filter, with it's unique design and mounting location, allows the filtering screen to be scrubbed while in operation, providing maximum maintenance intervals with unmatched performance capabilities. 

optional filter socks for pressure filter to protect septic system from hair and lint

Servicing a filter with socks is even easier than the screen alone.

The filter screen is a type 316L stainless steel with .062" diameter holes. The filter cartridge is 3 inches in diameter and 18 inches long with a 69.52 square inch open area. This large 41% open area allows the filter to pass 83.8 gallons per minute at 1 psi. With features like these even a partially clogged screen will keep the system well protected and working properly. This performance product assures quality effluent with lower TSS levels, keeping your pressurized distribution system functioning at 100% efficiency.  Optional filter socks are available for use with the screen to filter down to 600, 190, or 100 microns (.024”, .007”, .004”).  The pressure filter protects any pressurized distribution system including Sanitary Mound Systems, Sand Filters, Spray Irrigation Systems, Drip Systems, Pressurized Chambered Systems, Commercial Pressurized Systems or any Pump Septic System, Wastewater Treatment Systems or Residential Pressurized Systems. The pressure filter should be used as a safe guard component in all pressurized septic systems. 

Filter Info

sim/tech filter pressure filter with stainless steel screen

Various Models Available


STF-100A2 pressure filter for onsite septic systems

This is the version sold 99% of the time.  It is also known as the "field assemble" version.  It has 2" solvent weld inlet and outlet ports.  This version allows the filter to be custom fit to the system as we recommend that the filter be installed as high in the tank as possible to make maintenance easier.


STF-100 pressure filter for onsite septic systems

This is the original version sold.  It is the easiest to install as it screws directly onto the pump.  However, it only has 10.5 inches of pipe glued into the inlet which does not raise the filter high enough in many systems which makes maintenance more difficult.


STF-100A4 pressure filter for onsite septic systems

This is a high volume pressure filter for systems that have horizontal space issues.  Previously, to accommodate higher flows, multiple filters could be put together into a manifold.  The filter is rated at about 250 gallons per minute at 2 psi. The inlets and outlets are 4” solvent weld.  The filter screen inside is twice as tall as the standard 100A2 so the filtering area is doubled.  If you lack the space to put in multiple 2” filters there is the STF-100A4 to handle your commercial size flow requirements.

(Note: This is a fabricated filter body unlike the molded 100A2 body.)


STF-100A2/U pressure filter for onsite septic systems

This is the same as the STF-100A2, except that the outlet has a factory installed 2" schedule 80 union to be used as a disconnect from your outlet pipe.  This is a standard method used in pump systems which allows the pump to be pulled from the system for any necessary pump maintenance.  You can install your own union or other disconnect on the 100A2.


STF-100A4 pressure filter for onsite septic systems

This is the same as the 100A2, except that the inlet and outlet are 3" solvent weld.  Because of the larger inlet and outlet it can handle a larger flow-rate of about 125 gallons per minute. 

(Note: This is a fabricated filter body unlike the molded 100A2 body.)

Filter Manifolds

pressure filter manifold for large size wastewater systems

Above shows a manifold installed outside a tank, this requires the o-ring style cap.

For high volume or high wastewater strength systems such as commercial or multi-family systems you can manifold the 100A2 filters.  Sim/Tech Filter can also build these manifolds for you.  You can manifold any number of filters to meet your requirements.  As a rough estimate you will need one filter per 80 gpm of flow rate.  Maintenance would be roughly every 50,000 gallons so you would need to take this into consideration for your desired maintenance interval length.

Optional Tools

metal service wrench for Sim/Tech pressure filters
plastic service wrench for simtech pressure filters

STF-150M metal wrench for removing the filter cap.  The wrench press fits to the filter cap preventing it from being dropped in the tank during removal.  Also makes removal easier as it adds 30 inches to your reach.

STF-150 plastic wrench for removing the filter cap.  The wrench press fits to the filter cap preventing it from being dropped in the tank during removal.  Also makes removal easier as it adds 30 inches to your reach.  (Note: Not recommended for use in temperatures under 35F.) 

Click through the gallery below to see Sim/Tech products in the field and more.

Watch a demonstration of the pressure filter below

Pressure Filter Demo Video

Watch a video on the pressure filters and orifice shields

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