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Green Drain™ · 3.5″/4″ · DN90-100

Green Drain™ 3.5″/4″
Combo seal.

3.5 and 4 inches / DN90–DN100 / internal grate diameter 90–100 mm

Second combo variant — fits both 3.5″ and 4″ P-traps. Optimal for large facilities where P-trap sizes are mixed between 90 and 100 mm.

48,99 € · VAT included
Price excluding VAT: 39,19 €
In stock in Zagreb · delivery 24–48 hours in HR, 3–5 days in the EU
Request a quote → Buy now →

Price includes Croatian VAT (25%). Businesses are invoiced VAT-exempt against a valid EU VAT number. Delivery: Croatia €9.99 · Slovenia €11.99 · Bosnia and Herzegovina €17.99 · Serbia €18.99. Rates apply to consignments up to 2 kg; for heavier consignments and other EU countries, send an enquiry.

R1 invoiceFor businesses
HACCP Int. RG-04NSF/ANSI 2SGS QDF25-0049810-01CE ETA-18/0536EU MDR 2017/745 (Class I)ASSE 1072-2020CSA B79-2008cUPC IAPMO 9301

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Technical specification

Green Drain™ 3.5″/4″ (GD-3.5/4) — silicone seal with ABS frame. All manufacturer specifications.

Size3.5″/4″ (DN90-100)
Seal materialMedical silicone
Frame materialUV and chemical resistant ABS
Built-in unit height50 mm
Maximum flow323,17 L/min
Temperature range−40 °C to +100 °C (briefly 120 °C)
Seal life5 years with normal use
ASSE 1072 cycles2,500+ test cycles
Aerosol Blockage (SGS)99.9% MS2 surrogate
Packaging1 piece in a box + instructions
Weight110 g

What is Green Drain™?

Patented one-way silicone seal that is installed in the body of an existing floor drain. Under the weight of water it opens downward, and at rest it remains hermetically sealed upward—physically blocking sewer gases, viral aerosols, and insects.

No water in the P-trap, no chemicals, no maintenance. Medical-grade silicone, proven long-lasting durability, SGS-tested to block >99.9% of MS2 viral surrogates.

Learn more about Green Drain™ →
Green Drain™ cross-section
Technical cross-section

Where to use it.

Large facilities with mixed 3.5″/4″ P-traps — one SKU covers both, reducing inventory holding.

Professional kitchens

Hot line, prep area, cold kitchen (garde manger)

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Hotel Bathrooms and Wellness

Shower stalls, hammams, spa

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Hospital shower enclosures

Standard 3″ sink drain in the rooms

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Sports halls

Shower enclosures for high schools, universities, and fitness centres.

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Wine Cellars

Standard basement and overflow room drain

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DDD interventions

Mechanical barrier for fruit and drain flies

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View all 18 industries →

Detailed sector guide with recommendations on sizing, EU certifications, and HR regulations.

Installation in 30 seconds.

No plumber needed. No tools. No cutting into existing pipes. DIY or professional installation.

Step 1 — Remove the grate
Step 1
Take off the grate.
Remove the existing grate or strainer from the drain.
Step 2 — Insert Green Drain
Step 2
Insert Green Drain™
Lower the silicone seal 5–10 cm into the drain body.
Step 3 — Press
Step 3
Press on the spot
Silicone ribs adjust to the diameter. It works immediately.
Step 4 — Put the grate back
Step 4
Return the grate
Done. 30 seconds of work, lasting security.

Questions about this size.

Customer Frequently Asked Questions for GD-3.5/4.

GD-3.5/4 silicone ribs are expanding — they compress and expand inward until they fill the P-trap. They seal at both the smaller (3.5″) and the larger (4″) diameter.
No. The GD-3.5/4 leaks 323,17 L/min—more than a normal load delivers at once. The seal opens downward under the weight of the water.
Wet cloth for regular floor cleaning. The seal remains in the drain; the grate is removed from above it. Visual inspection once a year.
Yes. Silicone is resistant to sodium hypochlorite up to 5%, quaternary amines, isopropanol, and ethanol at standard food service and hospital concentrations.
Yes. Green Flow d.o.o. is the exclusive distributor of Green Drain™ for the Adria region. Each unit comes with the manufacturer's original QR code and serial number.

Not sure if 3.5″/4″ is your size?

Send us a photo of your P-trap and our technical support will recommend the exact size — free of charge, the same business day.

GD 3.5–4″ fits a drain body with an internal diameter of 90–100 mm. If your measurement falls in that range, this is your size.
1
Lift the grate

Take out the existing grate or strainer. Underneath is the drain body — the pipe the seal drops into.

2
Measure the internal diameter

Measure the pipe opening, not the grate. The grate is always wider, and that is the single most common reason people order the wrong size.

3
Match it to a range

Find the size whose range your measurement falls into. If you are between two, take the smaller one — the silicone ribs expand.

No tape measure to hand? A strip of paper works: wrap it around the opening, mark where it overlaps, measure that length and divide by 3.14. And if you still get the size wrong, there is a 14-day return — send it back and we swap it, no questions.

Send photo → All sizes