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Green Drain GD35 waterless trap seal for 3.5-inch kitchen floor drains
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GD35

3.5" Waterless Trap Seal

Fits 3.5" (89-95 mm) drain outlets. Highest flow rate under 4 inches at 323.17 L/min. Drop-in install, no tools required.

$44.95

Free shipping on all US orders

Pipe Size 3.5" (89-95mm)
Flow Rate 323.17 L/min
Install Time 30 Seconds
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Will it fit? Measure the pipe opening under the cover, inside wall to inside wall.

Watch how to measure Size chart
Green Drain measuring keychain with a cutout for each drain size

Measuring keychain $6.95A cutout for every size, so you order the right one.

Size chart

Measure the pipe opening inside wall to inside wall, then find the row your reading falls in. Go by the millimeters: the inch size is only the pipe’s name.

ModelPipe openingSize
GD12532 to 38 mm1.25"
GD1539 to 47 mm1.5"
GD251 to 59 mm2"
GD2555 to 65 mm2.5"
GD368 to 81 mm3"
GD35 this page89 to 95 mm3.5"
GD499 to 107 mm4"
GD5125 to 133 mm5"
GD6149 to 157 mm6"
International models, by quote
GD3/3577 to 95 mm3 to 3.5"
GD35/489 to 108 mm3.5 to 4"

Full measuring guide
cUPC Listed
HACCP Certified
Free US Shipping

For hospitals and clinics: GD-MD, the medical version of this size.

Inspect the seal around 6 to 12 months in service to confirm the silicone is still intact and sealing properly. Replace only as needed: high-use drains wear sooner, while low-use drains often last a year or longer.

Cutaway view of a 3.5-inch floor drain and its trap

How it works.

Green Drain is a one-way valve for your floor drain. Water flows down and out. Nothing comes back up.

Inside sits a soft silicone valve. Running water pushes it open; the moment the water stops, it closes and seals tight against sewer gas, odors, and pests. Because it seals with silicone instead of water, it never dries out the way an ordinary trap can, even when the drain goes weeks without use.

It fits 3.5-inch drains, 89 to 95 mm, and drops in by hand. No tools, no plumber, installed in seconds.

Will it fit? Measure first

Measure the pipe. Not the grate, not the bowl.

Lift the grate. At the bottom of the drain body is a round pipe opening. Measured across its center from inside wall to inside wall, that is the only number that matters. The GD35 seats in a pipe of 89 to 95 mm (3.5 in.). If the opening is oval, use the smaller reading. Outside that range, another size fits: see all sizes.

Drain in section with the grate highlighted: not the part to measure

Don't measure the grate

The grate is the cover you walk on. It sits on top of the drain body and is wider than the pipe underneath, so its width tells you nothing about fit.

Drain in section with the bowl highlighted: not the part to measure

Don't measure the bowl

The bowl is the basin under the grate that funnels water down. It is wider than the pipe too. The Green Drain does not sit here.

Drain in section with the pipe highlighted: the part to measure

Measure the pipe

At the bottom of the bowl is the round pipe opening. This is where the Green Drain seats, so this is the width to measure. Wipe it clean, then measure inside wall to inside wall.

Floor drain from above with the grate off: a tape across the pipe opening from A to B
Measure A to B. The pipe opening at the bottom of the bowl.
How to Measure and Install a GD35. Measure first, then install. Jump to either part below the video.

Full installation guide: how to measure, choose a size and install.

Common drains it fits
GD35 installed in a round floor drain
Round
GD35 installed in a square floor drain
Square

Not seeing your drain? If its outlet is a round pipe in the GD35's range, it fits. The cover on top does not matter; the pipe under it does. Remove any basket or strainer first.

GD35 in section with water flowing down through the open skirt
Water flowing. The silicone skirt opens and water passes.
GD35 in section with the skirt closed and sewer gas held below
Flow stopped. The skirt closes. Air, odor and insects stay below.
The valve, two states

One-way. Opens for water going down, closes when the flow stops. No water to top up, no power, nothing to prime.

Inspect the seal around 6 to 12 months in service and replace only as needed.

Installs in 30 seconds. No tools.

1
Step 1: the grate lifted off a floor drain, shown in section

Lift the grate

Most grates lift straight out by hand. Some are held by one center screw; back it out, then lift.

2
Step 2: measuring the pipe opening at the bottom of the drain, inside wall to inside wall

Measure the opening

Measure the pipe opening at the bottom of the bowl, inside wall to inside wall. The GD35 fits 89 to 95 mm (3.5 in.).

3
Step 3: the GD35 being pressed down into the pipe opening

Press it in

Push the Green Drain into the pipe by hand until it sits 2 to 4 inches (50 to 100 mm) below the top of the pipe. The silicone gasket creates a snug seal against the pipe walls.

4
Step 4: the grate back in place over the seated GD35

Replace the grate

Put the grate back. Done. Nothing to wire, prime or top up, and a full commercial floor takes an afternoon. Lifts out by hand, or with the extraction tool.

Watch the install for the GD35 It starts at 0:53 in the video above.

Built for high-volume drainage.

Independently tested performance data. The GD35 delivers 3x the flow capacity of the GD3 at Level U.

323.17 L/min Flow Rate (Level U) 3x the flow capacity of the GD3.
502 Pa Pressure Resistance DTI tested back-pressure rating.
200 Pa Odour Tightness CE/ETA certified gas-tight seal.
>2,500 Cycle Life ASSE 1072 durability tested.
For Architects & Engineers

Specify Green Drain in your next project.

Download the Revit family set for every Green Drain model, and find us listed in BSD SpecLink and MasterSpec.

Download Revit Families View full specifications →

Technical Specifications

ModelGD35
Pipe Size3.5" (89-95 mm)
Height50 mm
Housing Diameter (no gasket)78.75 mm (3.100"), bottom 83.6 mm (3.291")
Housing with Gasket97.46 mm (3.837") wide x 50.82 mm (2.001")
Housing MaterialABS Plastic
Valve MaterialSilicone Rubber
Seal MaterialSilicone Gasket
Flow Rate323.17 L/min
Pressure Resistance (DTI)502 Pa
WaterMark LicenseWM-022837 (DN90)
PatentsMultiple US & international patents

Industries we serve.

The GD35 fits 3.5" (89-95 mm) drain outlets.

Restaurants & Food Service Food & Beverage Manufacturing Breweries & Wineries Industrial & Manufacturing

Certifications and compliance.

Green Drain cUPC certification - IAPMO File 9301 ASSE 1072-2020

cUPC Listed

IAPMO File 9301

ASSE 1072-2020 Standard

Barrier-type trap seal performance standardEvaluated under IAPMO R&T cUPC File No. 9301

Green Drain CE Mark European Technical Assessment ETA-18/0536

CE / ETA-18/0536

European Technical Assessment

Green Drain NSF/ANSI 2 food equipment certification

NSF/ANSI 2

Food Equipment Certified

Green Drain HACCP International food safety certification

HACCP International

Food safety certification (Certificate RG-05)

Green Drain WaterMark Australia certification WM-022837

WaterMark Australia

WM-022837 (DN90)

Green Drain California Proposition 65 compliance declaration

Prop 65 Compliant

California compliance declaration

SGS

SGS Aerosol-Retention Test

Retained over 99.9% of an aerosolized MS2 bacteriophage viral surrogate

Green Drain tested by Danish Technological Institute DTI

DTI Tested

Rapport 957187

Green Drain IAPMO R&T certified plumbing product

IAPMO R&T

Certified Testing Lab

Green Drain VA Godkendelse Danish plumbing approval

VA Godkendelse

Danish Plumbing Approval

View All Certifications

For architects and engineers.

Write the GD35 into a specification by name. Its spec sheet puts the dimensioned plan and section views, the engineering specification paragraph, performance data and listings on one page. The spec pack adds every model, with the certificates and test reports.

Spec Section 22 13 19
Basis of Design Green Drain GD35, IAPMO File 9301
Patents Multiple US & international patents
Download the GD35 spec sheet Download the full spec pack

PDF. Spec sheet: 1 page. Spec pack: 72 pages, 12 MB. See every model's specifications

The GD35 spec sheet in front of the Green Drain Product Specification Pack

Related products.

Green Drain GD3 waterless trap seal for 3-inch floor drains

GD3 (3")

 Green Drain GD4 waterless trap seal for 4-inch floor drains

GD4 (4")

 Green Drain GD5 waterless trap seal for 5-inch floor drains

GD5 (5")
View All Products

Ready to protect your drains?

Drop-in install. No tools. Works from day one.

Add GD35 to Cart Request a Quote