In a controlled bench test by SGS, the Green Drain GD3 retained over 99.9% of an aerosolized MS2 bacteriophage viral surrogate at the drain opening. As a waterless one-way valve, Green Drain restricts the retrograde movement of air and aerosols from the drainage system into the occupied space. Surrogate retention is a physical bench-test result and is not a measure of pathogen retention or infection protection.
Floor drains connected to building sewer systems can act as pathways for air and aerosols moving from the drainage system into occupied spaces. When trap seals dry out or fail, air from the sewer system can rise through the drain opening. This is not a theoretical concern. Published research has documented drain-to-air pathogen transmission in hospitals, commercial kitchens, and multi-story buildings.
The SGS aerosol-retention test measured how much of an aerosolized viral surrogate physically moved through the drain opening with and without a Green Drain installed. Using MS2 bacteriophage (ATCC 15597-B1) as a standardized viral surrogate, the test aerosolized the surrogate particles and measured how many passed through a drain pipe with and without a Green Drain GD3 installed. The result: with the GD3 in place, the internal gas measured behind the trap seal fell below detection limits in all three test rounds. This is a physical measurement of aerosol movement; it does not measure pathogen retention or infection risk.
MS2 bacteriophage is a standard test particle used in laboratories referencing U.S. EPA, CDC, and WHO methods for evaluating filtration and barrier performance. At approximately 27 nm in diameter, MS2 is similar in size to influenza and SARS-CoV-2. Critically, MS2 is a non-enveloped RNA virus, making it physically robust and harder to retain than most real-world respiratory viruses (which tend to be enveloped and more fragile), which makes it a conservative choice as a bench-test particle. Retention of the MS2 surrogate is a physical result and is not the same as retention of real-world pathogens, and no bench test of this kind measures infection risk.
The SGS aerosol-retention test (Report QDF25-0049810-01) was conducted at SGS-CSTC Standards Technical Services in Qingdao, China, an ISO/IEC 17025:2017 accredited laboratory (CNAS Registration L0604). Testing was performed between June 17 and June 23, 2025.
The test setup used a PVC pipe with a 75mm inner diameter, matching the GD3 model. Two configurations were tested side by side. In the test group, the pipe was sealed at the top with a sealing cap and the GD3 trap seal was installed at the bottom. In the control group, the pipe was sealed at the top but left open at the bottom with no trap seal. Both pipes were placed in separate 1 cubic meter air chambers.
MS2 bacteriophage (ATCC 15597-B1) was aerosolized and sprayed into each chamber. A small fan blew air toward the bottom of each pipe, simulating the positive pressure that occurs in building sewer systems (sewer gas pushing upward through drain openings). Each exposure period lasted 10 minutes.
After exposure, the outer surfaces of each pipe were disinfected and the pipes were transferred to a biosafety cabinet. The internal gas collected inside each pipe was then tested for MS2 bacteriophage content using plaque-forming unit (PFU) assay, which counts the number of viable virus particles present.
The results were consistent. In round one, the control pipe contained 72,500 PFU while the test pipe with the GD3 measured below 5 PFU. In round two, the control measured 62,000 PFU against below 5 PFU with the GD3. In round three, the control measured 18,000 PFU against below 5 PFU. Across all three rounds, the GD3 retained over 99.9% of the aerosolized MS2 viral surrogate.
The SGS aerosol-retention data is most relevant in environments where the movement of air and aerosols through drain systems is a concern for occupant comfort, indoor air quality, or regulatory compliance:
Hospital floor drains are documented vectors for pathogen transmission. Published studies have linked drain systems to outbreaks of carbapenem-resistant organisms (CROs), MRSA, and other healthcare-associated infections. A waterless one-way valve that restricts the retrograde movement of air and aerosols from the drainage system, and that retained over 99.9% of an aerosolized viral surrogate in this bench test, is relevant as a supportive engineering control alongside infection-prevention programs. It complements, and does not replace, those programs.
In food processing and commercial kitchens, facilities operating under HACCP protocols work to control hazards at every point in the production environment. Floor drains are one pathway by which air and aerosols move from the drainage system into the space. This test data supports Green Drain's HACCP International endorsement with a measurable, independently run bench-test result.
Building owners and facility managers are increasingly focused on indoor air quality and how air moves through building systems, particularly following the COVID-19 pandemic. This test provides a quantified bench-test measurement of how much of an aerosolized surrogate the trap seal retains at the drain opening. For specifiers, this is a differentiator: most waterless trap seal competitors do not have published aerosol-retention test data from an accredited laboratory.
Download the full SGS test report (QDF25-0049810-01) documenting over 99.9% retention of an aerosolized MS2 bacteriophage viral surrogate, along with the laboratory's ISO/IEC 17025 accreditation certificate.
In a controlled bench test, the Green Drain GD3 retained over 99.9% of an aerosolized MS2 bacteriophage viral surrogate. In all three test rounds conducted by SGS, the internal gas measured behind the GD3 fell below the detection threshold (less than 5 PFU), compared to control readings of 18,000 to 72,500 PFU with no trap seal installed. This is a physical measurement of how much of the aerosolized surrogate moved through the drain opening; surrogate retention is not a measure of pathogen retention or infection protection.
MS2 bacteriophage (ATCC 15597-B1) is an internationally recognized viral surrogate used in filtration and barrier research. It is used by laboratories referencing U.S. EPA, CDC, and WHO methods because it is similar in size to influenza and SARS-CoV-2 (approximately 27 nm diameter), is non-enveloped and physically robust, and is safe to handle in a laboratory (Biosafety Level 1). Its value is as a standardized physical test particle in a controlled bench setting. Retention of the MS2 surrogate is not the same as retention of real-world pathogens, and the bench test does not measure infection risk.
The test was conducted by SGS-CSTC Standards Technical Services (Qingdao) Co., Ltd., an ISO/IEC 17025:2017 accredited laboratory (CNAS Registration L0604). The lab's CNAS accreditation is backed by ILAC MRA signatory status, meaning test results are internationally recognized across member countries.
All 8 Green Drain models share the same design. Testing was performed using the GD3 (3-inch) as the representative model, installed in a PVC pipe with a 75mm inner diameter in a 1 cubic meter air chamber. Because all models use the same silicone membrane sealing mechanism, the same one-way valve behavior that restricts the retrograde movement of air and aerosols applies across the full product line.
Yes. Hospital and building floor drains have been documented as vectors for pathogen transmission. Published studies have linked drain systems to outbreaks of carbapenem-resistant organisms, MRSA, and other healthcare-associated infections. As a waterless one-way valve, Green Drain restricts the retrograde movement of air and aerosols from the drainage system into the occupied space; in the SGS bench test it retained over 99.9% of an aerosolized MS2 viral surrogate. It is a supportive engineering control that complements, not replaces, an infection-prevention program.
Download the SGS report directly, or contact us for specification language, technical documentation, or project-specific support.