Ultra XP RO-4040

Not every commercial or industrial RO system needs — or has room for — an 8 inch membrane element. Smaller footprint systems, point-of-use commercial units, and installations with tighter housing space still need dependable, high-purity output, just at a scale that matches their actual demand. The Ultra XP RO-4040 is a TFC (thin-film composite) spiral-wound reverse osmosis membrane in the industry-standard 4 inch diameter, 40 inch length format, delivering up to 2,500 GPD (roughly 395 LPH) of flow capacity while rejecting up to 99.5% of dissolved salts and TDS. Its low-fouling design is built for the same demanding commercial, industrial, and process water conditions as Pearl Water's larger Ultra XP RO-8040, just sized for systems where a compact 4040 housing footprint is the better fit. If you're specifying or replacing a membrane for a standard 4040 housing and need high purity without oversizing your system, this is the straightforward choice.

What Does "4040" Mean in an RO Membrane?

"4040" is standard industry shorthand for a membrane element's physical dimensions: a 4 inch diameter and a 40 inch length. It's a universal sizing convention, not a brand or performance claim — used across manufacturers including Dow Filmtec, Toray, Hydranautics, CSM, and GE, which is why a properly rated 4040-format membrane will typically fit any standard 4040 housing regardless of make. Within that shared size, individual models differ on flow capacity, salt rejection, and fouling resistance — the Ultra XP RO-4040 is built toward the higher end of all three for its size class.

What Is the Ultra XP RO-4040 Membrane?

The Ultra XP RO-4040 is a spiral-wound reverse osmosis membrane element built around a compact 4-inch diameter and 40-inch length, engineered for reliable, long-lasting purification in a smaller physical footprint than industrial-scale elements. As feed water is forced through the membrane under pressure, dissolved salts, minerals, and other impurities are rejected while purified water (permeate) passes through — the same core reverse osmosis principle used across every scale of RO system, from a domestic purifier to a full industrial RO plant.

What sets a membrane like this apart within its size class is the combination of throughput and rejection quality it can sustain. At up to 2,500 GPD and up to 99.5% salt rejection, the Ultra XP RO-4040 is positioned for commercial, industrial, and municipal applications that need genuinely high-purity output but don't require — or don't have space for — an 8-inch element. Its low-fouling membrane surface is engineered specifically to minimize scaling and organic buildup, extending usable life between cleanings and reducing the maintenance burden that comes with a fouling-prone element.

How Does It Work?

1. Pressurized feed water enters the membrane housing and flows across the spiral-wound membrane surface.

2. Water molecules pass through the semi-permeable membrane under pressure, while dissolved salts, minerals, and larger molecules are rejected.

3. Purified permeate is collected through the membrane's central tube and directed to the system outlet.

4. Concentrated reject water carrying the rejected salts is flushed out separately, preventing buildup on the membrane surface over time.

5. The low-fouling surface resists scale and organic deposits during this process, helping the membrane maintain both flow rate and rejection performance for longer between cleaning cycles.

Feed water quality, applied pressure, and upstream pre-treatment all directly influence how close actual performance tracks to the membrane's rated 2,500 GPD and 99.5% rejection figures — which is why pairing this element with proper sediment and carbon pre-filtration matters as much as the membrane spec itself.

Buying Guide: Choosing the Right Membrane

Match the membrane to your housing size. This element fits standard 4040 housings (4 inch diameter, 40 inch length) — confirm this is your system's format before ordering.

Assess your actual daily water demand. If your facility's requirement sits at or below roughly 2,500 GPD per element, the 4040 avoids the cost and space overhead of oversizing with an 8040.

Consider space constraints. Smaller mechanical rooms, retrofit installations, or systems with limited housing space benefit directly from this element's compact footprint.

Factor in feed water quality. The low-fouling design performs best when paired with proper upstream sediment and carbon pre-treatment, protecting the membrane from particulate and chlorine-related damage.

Plan for scaling. If demand might grow, consider whether a multi-element 4040 array or a future move to an 8040 format makes more sense than over-ordering now.

Key Features

• Up to 2,500 GPD flow capacity — strong throughput for a compact 4-inch element.

• Up to 99.5% salt rejection — reliable removal of dissolved salts and TDS for consistently high-purity output.

• Standard 4040 sizing (4 inch diameter, 40 inch length) — fits standard commercial and industrial 4040 membrane housings without modification.

• Low-fouling membrane design — resists scaling and organic buildup, reducing cleaning frequency and extending service life.

• Space-efficient footprint — suited to systems where housing space is limited but purity requirements aren't.

• 1 year warranty and 10-day replacement window — backed by Pearl Water's standard product assurance.

Ultra XP RO-4040 vs Ultra XP RO-8040

If your facility's daily water demand is modest, or your housing space is limited, the 4040 is generally the more practical and cost-efficient choice. Once demand scales toward several thousand gallons per day, the Ultra XP RO-8040 becomes the better fit, since a single 8040 element can outperform multiple smaller units without adding housing complexity.