







💧 Elevate your water game—purity and power in one sleek membrane!
The Max Water ULP-4040 is a high-capacity 4" x 40" reverse osmosis membrane designed for commercial, industrial, and agricultural water purification. Delivering up to 2600 gallons per day with a 99.35% impurity rejection rate, it operates efficiently under pressures up to 600 psi. Certified ISO 9001 and constructed with BPA-free materials, this durable membrane ensures safe, long-lasting performance with advanced thin film composite technology.

















| ASIN | B07GZTZVFR |
| Best Sellers Rank | #37,356 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #275 in Replacement Under-Sink Water Filters |
| Brand | Max Water |
| Customer Reviews | 4.5 4.5 out of 5 stars (216) |
| Date First Available | October 16, 2021 |
| External Testing Certification | ISO 9001 |
| Item Weight | 6.93 pounds |
| Item model number | Commercial Membrane |
| Manufacturer | Max Water |
| Material | Fiberglass |
| Number of Items | 1 |
| Product Benefits | Removes impurities for improved water quality |
| Product Dimensions | 3.94"D x 3.94"W x 39.76"H |
| UPC | 680392199928 |
| Unit Count | 1.0 Count |
A**L
Very good quality
I bought these for my reverse osmosis system and it has been working with amazing results.
Y**.
El producto llegó en buen estado y a tiempo, buena calidad
G**A
Works very well.
Works very well. First one lasted almost a year with nasty well water.
J**L
Works great
Pretty impressed with the quality for the price, came with mounting straps also, works great, no complaints.
R**Y
Less water usage
A lot more RO Water, and less water sent down the drain. Replace the 21 inch.
F**N
Excellent Membrane for brackish water
This product is excellent i got it on time like they say and in order no damages I'm a happy customer and will purchase again and will recommend this product to family and friends
P**L
After 6 months of use review
The first time I used the pair of membranes, since I bought 2 of them to double water output, they worked great. My local municipal water has tds levels in the 500-750 ppm range with most days being in the 500-600 range. In the first month, my permeate ppm range was between 0-15 ppm at most, and didn’t use DI resin much to wash cars or my solar panels. Unfortunately, after 6 months of use, my permeate has steadily increased from the 0-15 ppm level to 80-95 ppm. It still removes about 80% of tds, but 20% leakage is already telling me that it’s time to replace what are lightly used membranes. I use a 20x4.5 sediment filter, and a 20x4.5 carbon block filter to ensure that no elements that can ruin these membranes get through. My usage is mostly for washing 1 or 2 cars, and periodic solar panel cleaning during the weekends, meaning that I use less than 100 gallons of permeate in each weekend event. Membranes are kept wet, and not used for drinking, even though I would feel comfortable drinking from them. Operating pressure ranges from 50 psi (municipal) to 120 psi via pump for pressure boosting when needing to increase water output. I didn’t think it would be fair for me to write a 1 or 2 star review without giving the seller a chance to respond first, privately through their website, but after 3 weeks, and no response from them, I believe that it’s fair to share my experience with anyone interested in considering this commercial RO membrane. I’ll be looking for a different manufacturer, even if I have to pay an extra $100 dollars for 2 membranes of the 4x40 size. By the way, the plastic end-caps cracked, even though I didn’t torque them much. The leaks are not from the circumference, but from the threaded fittings. I have replaced 8 caps at my own expense, and the last 4 are not leaking, but they required lots of teflon and a gentle hand to avoid cracking them. The cracks are almost not visible with the naked eye, but you’ll see the water leaking when pressurized, and they come from the threaded holes closes to the edge for the most part. I would suggest that it may be best to create a metal end cap. I’m sure it will be heavier and more expensive, but it will last a long time, and I care more about reliability than disposability. Unfortunately, plastic runs the risk of cracking each time the end caps are removed to service the membranes since the seals are tight. A metal end cap can take more punishment without cracking, and it’s a once and done deal.
S**.
excelente a buen precio
R**B
Used one of these membranes in a maple RO for 3 years so far. Works well. I always check for passing sugar and it continues to stay at 0
A**C
Using it in my whole house RO system. works like original
A**.
Conforme au dimensions, livraison rapide
C**S
We used this as replacement membrane in on whole house RO system and it failed in less than a month. Previous membranes have lasted a year or more. Support tried to blame our system until we sent them our setup and then they said there is no warranty because of a "high likelihood of factory failure"
J**N
I Use this item on my water conditioning machine. Lasts up to one year
Trustpilot
3 days ago
3 weeks ago