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Dow FILMTEC and Hydranautics RO Membrane Suppliers in India

Brackish water, seawater and low-fouling reverse osmosis elements in 4040 and 8040 sizes, supplied across India by QuaSys Inc.

RO Membranes for Water Treatment and Desalination

Reverse osmosis (RO) removes dissolved salts, TDS and most dissolved contaminants by forcing water through a semi-permeable membrane. QuaSys Inc. supplies RO membrane elements from two makes, Dow FILMTEC and Hydranautics, for industrial process water, boiler feed, drinking water, desalination and water reuse. As a supplier of commercial reverse osmosis and UF membranes, we can also match the right Grafil UF membrane as pre-treatment.

RO Membrane Makes We Supply

Dow FILMTEC FILMTEC polyamide thin-film composite elements, now sold under DuPont Water Solutions (formerly Dow). Families include BW30 and XLE for brackish water, SW30 for seawater and TW30 for tap water.

Hydranautics Hydranautics, a Nitto Denko Group company. Families include CPA and ESPA for brackish water, LFC for low fouling and SWC for seawater desalination.

RO Membrane Families

Make	Family	Used for
FILMTEC	BW30	High-rejection brackish water RO
FILMTEC	BW30LE, XLE	Low and extremely low energy brackish water RO, for lower operating pressure
FILMTEC	SW30	Seawater RO, and high-salinity brackish water
FILMTEC	TW30	Tap water and light commercial systems
Hydranautics	CPA (Composite Polyamide)	High-rejection brackish water RO
Hydranautics	ESPA (Energy Saving Polyamide)	High flux at lower pressure with high rejection
Hydranautics	LFC (Low Fouling Composite)	Municipal and industrial wastewater with organic fouling potential
Hydranautics	SWC (Seawater Composite)	Seawater desalination

Both makes are offered in 4-inch and 8-inch diameter elements, 40 inches long (4040 and 8040). Exact models in stock, and any model not listed, are confirmed when you send your requirement.

How to Read an RO Element Name

In FILMTEC names such as BW30-4040, the first part is the membrane type (BW30 is a brackish water membrane) and the second part is the element size: 4040 means 4 inches in diameter and 40 inches long. Hydranautics names follow the same idea, for example ESPA2-4040 or CPA3 for an 8-inch element.

Brackish Water vs Seawater RO

	Brackish water RO	Seawater RO
Feed salinity	Low to medium TDS	High salinity, such as seawater
Operating pressure	Lower	Much higher
Typical makes and families	FILMTEC BW30, XLE; Hydranautics CPA, ESPA	FILMTEC SW30; Hydranautics SWC
Typical use	Process water, boiler feed, drinking water, reuse	Desalination

Pretreatment Matters

RO membranes need clean feed water. A typical train uses multimedia and cartridge filtration, and ultrafiltration where suspended solids or turbidity are high. Residual free chlorine must be removed before the RO, since polyamide membranes are not chlorine tolerant. For effluent reuse, RO usually sits downstream of MBR or UF. See our UF vs MBR guide for how these steps fit together.

What We Need to Recommend an RO Membrane

Feed water source and TDS analysis
Temperature and required permeate flow
Pretreatment already in place
New plant or replacement element, and the make and model installed

Applications

Industrial process water and boiler feed water
Drinking water and commercial systems
Seawater and brackish water desalination
Treated wastewater reuse after MBR or UF

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Enquire with QuaSys Inc. for water treatment equipment quotes

Specifications & pricing last verified: 03 Jul 2026

Frequently Asked Questions — RO Membrane

Which RO membrane brands does QuaSys Inc. supply?+

QuaSys Inc. supplies Dow FILMTEC and Hydranautics RO membrane elements across India. FILMTEC is now sold under DuPont Water Solutions (formerly Dow), and Hydranautics is a Nitto Denko Group company. Call +91 95408 15659.

What is the difference between brackish water and seawater RO membranes?+

Brackish water membranes (FILMTEC BW30, Hydranautics CPA and ESPA) treat feed water with lower salinity at lower pressure. Seawater membranes (FILMTEC SW30, Hydranautics SWC) are built for high salinity and run at much higher pressure.

What does RO membrane size 4040 or 8040 mean?+

The first number is the element diameter in inches and the second is the length in inches, so 4040 is 4 inches by 40 inches and 8040 is 8 inches by 40 inches. In a FILMTEC name such as BW30-4040, the first part (BW30) shows the membrane type.

Do I need pretreatment before an RO membrane?+

Yes. RO needs clean feed water. Typical pretreatment is multimedia and cartridge filtration, and ultrafiltration where suspended solids are high. Residual free chlorine must also be removed, because polyamide RO membranes are not chlorine tolerant. QuaSys Inc. also supplies Grafil UF membranes for RO pre-treatment.

Which RO membrane is suitable for wastewater reuse?+

For reuse after biological treatment and MBR or UF, low-fouling elements such as Hydranautics LFC are designed for municipal and industrial wastewater with organic fouling potential. The right element depends on your feed analysis, so share it with us.

What information do you need to recommend an RO membrane?+

Your feed water source and TDS, temperature, required permeate flow, pretreatment in place, and whether this is a new plant or a replacement element. QuaSys Inc. does not publish fixed prices online; we send a specification-based quote.