sandmonk bw-rl4040 industrial ro membrane, [99.6% salt rejection] [4 x 40 inch] 2500gpd commercial industrial reverse osmosis filter replacements for brackish water desalination, wastewater recycling bw4040 225psi is up for auction in Industrial & Scientific. The current bid is $1.00, 99% below the $98.99 MSRP, in New/Like New condition. Bid on this item at our Elizabethtown - Peterson Drive location before the auction closes.