Franklin FWME4040RO-BW Brackish Water RO Membrane

4040 Brackish Water RO Membrane for High-TDS Well and Industrial Use

Standard low-pressure membranes top out at around 2,000 mg/L TDS. If your well water, coastal groundwater, or industrial source runs higher, you need a brackish water membrane. The Franklin Water FWME4040RO-BW brackish water RO membrane handles feed water up to 5,000 mg/L TDS with 99.6% salt rejection at 225 psi, producing 2,500 GPD from 85 ft² of active membrane area in a standard 4 x 40 element. 

Quick Specs

• Membrane Type: Thin-Film Composite (TFC), Brackish Water

• Element Size: 4" x 40" (standard 4040 format)

• Active Membrane Area: 85 ft² (7.9 m²)

• Permeate Flow Rate: 2,500 GPD (9.5 m³/d)

• Stabilized Salt Rejection: 99.6%

• Standard Test Pressure: 225 psi (1.55 MPa)

• Maximum Feed TDS: 5,000 mg/L

• Certification: NSF/ANSI 61

Key Features and Benefits

• 99.6% stabilized salt rejection, the strongest high salt rejection 4040 RO membrane in the Franklin Water lineup, handles brackish well water, mineral-heavy groundwater, and industrial sources up to 5,000 mg/L TDS.

• Rated for feed water up to 5,000 mg/L TDS, more than double the capacity of ULP and XLP membranes. If your water report exceeds 2,000 mg/L, this is the high TDS RO membrane to spec.

• Produces 2,500 GPD from 85 ft² of active area at 225 psi, a reliable 2,500 GPD brackish water membrane that holds output on high-TDS sources where low-pressure elements drop off.

• Handles process water for electronics, power generation, steel, pharmaceutical, biotechnology, and petrochemical operations where consistent permeate quality is critical.

• NSF/ANSI 61 certified and built in a standard 4040 format that fits any compatible 4-inch pressure vessel. This BW 4040 RO membrane drops into the same housings used by Dow Filmtec BW30-4040, AXEON, and other industry-standard reverse osmosis membranes.

• Maximum feed flow of 3.6 m³/h (15.9 gpm), cleaning pH range of 1 to 13, and maximum operating pressure of 600 psi. Supports acid and caustic CIP cycles for scaling and fouling on high-TDS sources.

FWME4040RO-BW Specifications

Applications

• Brackish well water and coastal groundwater desalination

• Industrial process water for electronics, pharmaceutical, and chemical manufacturing

• Power generation boiler feed water treatment

• Steel and metals manufacturing process water

• Food and beverage production from high-TDS source water

• Cooling tower makeup water treatment

• Water reuse and reclamation systems

• Pre-treatment stage for high-purity water production

Industries

• Municipal and industrial water treatment

• Power generation

• Pharmaceutical and biotechnology

• Electronics and semiconductor manufacturing

• Petrochemical and chemical processing

• Food and beverage production

• Steel and metals manufacturing

Buy the Franklin Water FWME4040RO-BW Online from Cleanflow

When your feed water TDS exceeds what low-pressure membranes can handle, the FWME4040RO-BW is the brackish water reverse osmosis membrane to spec for commercial and industrial systems. At 2,500 GPD with 99.6% rejection and NSF/ANSI 61 certification, it is the desalination RO membrane to specify when your source water TDS exceeds 2,000 mg/L. 

Cleanflow Utility Supply Company is an authorized Franklin Water Treatment distributor. The FWME4040RO-BW, compatible reverse osmosis system accessories, and replacement parts ship across Canada and the USA. Returns accepted within 30 days at returns.cleanflow.net.

Frequently Asked Questions

What TDS level requires a brackish water membrane instead of a low-pressure one?

Low-pressure membranes (ULP and XLP types) are rated for feed water up to about 2,000 mg/L TDS. Above that, rejection drops and output falls off. If your water report shows TDS between 2,000 and 5,000 mg/L, a 4040 brackish water membrane like the FWME4040RO-BW is the right choice. For TDS above 5,000 mg/L, you would need a seawater-rated element. For any 4040 system treating brackish groundwater, the FWME4040RO-BW is the well water RO membrane to specify.

What is the difference between a BW and an XLP membrane in the 4040 size?

The Franklin Water 4040 BW membrane operates at 225 psi and rejects 99.6% of salts from feed water up to 5,000 mg/L TDS. The 4040 XLP operates at roughly 100 psi and rejects 99.2% but is only rated for feed water up to 2,000 mg/L TDS. Choose BW when your source water has elevated dissolved solids, such as brackish well water or industrial process water. Choose XLP when your source is clean municipal or low-TDS groundwater and energy savings matter more.

Can I use the FWME4040RO-BW on well water?

Yes, if your well water TDS falls between roughly 1,000 and 5,000 mg/L. This Franklin Water brackish water membrane is specifically built for that range. Get a water analysis first. If your well water also has high iron, manganese, or hydrogen sulfide, you will need pre-treatment (oxidation and filtration) before the RO membrane to prevent fouling and damage.

Why does a 4 x 40 brackish water membrane element need more pressure than an XLP?

Higher TDS water creates more osmotic back-pressure across the membrane. To push water through against that resistance, the system needs more feed pressure. The FWME4040RO-BW is tested at 225 psi with 2,000 mg/L NaCl solution, compared to 100-150 psi for XLP and ULP elements tested at 500-1,500 mg/L. Your actual operating pressure depends on feed water TDS, temperature, and target recovery rate.

What pre-treatment does high-TDS feed water need before a brackish water RO membrane?

High-TDS water carries more dissolved minerals, which means higher scaling risk on the membrane surface. At minimum, install carbon pre-filtration for chlorine removal and sediment filtration for particulates. Cleanflow Utility Supply Company stocks compatible reverse osmosis filters for both stages. For brackish groundwater with elevated hardness, silica, or iron, add antiscalant dosing (a chemical that prevents mineral deposits from forming on the membrane) and consider a water softener upstream. Skipping pre-treatment on high-TDS sources shortens membrane life and voids most warranties.