Big Blue filter housings are among the most widely used water filtration components in residential, commercial, and light industrial applications worldwide. Their name comes from the blue translucent or opaque polypropylene housing that has become an industry standard for whole-house and point-of-entry filtration systems. Despite their simple appearance, choosing the right Big Blue housing and cartridge combination requires understanding several technical factors including size, flow rate, pressure rating, and application-specific needs. This guide breaks down everything you need to know.
A Big Blue filter housing is a large-format cartridge housing designed to accommodate standard 10-inch or 20-inch filter cartridges with a 4.5-inch diameter. The standard "Big Blue" designation typically refers to housings that accept 4.5-inch diameter cartridges, as opposed to standard 2.5-inch diameter cartridges used in smaller under-sink systems. The larger diameter means significantly more filter media surface area, which translates to higher dirt-holding capacity and lower pressure drop at equivalent flow rates.
The housings are most commonly made from polypropylene (PP) or reinforced polypropylene, with some heavy-duty variants constructed from stainless steel. They feature a sump design where the lower bowl unscrews from the head assembly for cartridge replacement. Most models include a pressure relief button or valve to safely depressurize the housing before servicing.
Big Blue housings have become the go-to solution for pre-filtration, whole-house filtration, and as guard filters before more expensive treatment equipment like water softeners and reverse osmosis systems. Jingze Water manufactures a complete range of Big Blue housings and compatible cartridges for markets across Asia, the Middle East, and Africa.
The two most common Big Blue housing sizes are the 10-inch and 20-inch versions. The number refers to the cartridge length the housing accepts. While they share the same 4.5-inch cartridge diameter, the length difference creates meaningful distinctions in performance and application.
| Parameter | 10-Inch Big Blue | 20-Inch Big Blue |
|---|---|---|
| Cartridge Length | 9.75 inches (nominal) | 19.75 inches (nominal) |
| Typical Flow Rate | 10-15 GPM (38-57 LPM) | 20-30 GPM (76-114 LPM) |
| Dirt-Holding Capacity | Baseline | 2x to 2.5x of 10-inch |
| Pressure Drop at 10 GPM | ~1.5-2.5 psi | ~0.8-1.5 psi |
| Space Required (Height) | ~16-18 inches | ~26-28 inches |
| Common Applications | Homes, apartments, small offices | Large homes, commercial, light industrial |
| Cartridge Replacement Cost | Lower per unit | Higher per unit, fewer changes |
The 10-inch Big Blue is suitable for most residential applications where peak demand does not exceed 15 GPM. This covers the vast majority of single-family homes with 1-2 bathrooms. The 20-inch version becomes necessary when you have a larger household, higher simultaneous water demand, or when you want longer intervals between cartridge changes. Many commercial kitchens, restaurants, and small manufacturing facilities use the 20-inch size because it can handle the higher flow rates typical of commercial fixtures.
One often overlooked advantage of the 20-inch housing is its lower pressure drop at the same flow rate. Because the water travels through twice the media depth, the velocity through the filter media is lower, which means less restriction. This can be critical if you have marginal water pressure coming into your facility.
Big Blue housings accept a wide variety of cartridge types, making them an extremely versatile platform. The most common categories include:
These remove suspended particles like sand, silt, rust, and pipe scale. They come in standard melt-blown polypropylene (PP), pleated polyester, and string-wound styles. Micron ratings typically range from 1 to 100 microns. The pleated style offers the longest service life because the folded media provides significantly more surface area than depth-style melt-blown or wound cartridges. For well water with high sediment loads, a 20-50 micron pleated sediment cartridge in a 20-inch housing is often the most practical pre-filtration solution.
Activated carbon block cartridges remove chlorine, taste, odor, volatile organic compounds (VOCs), and some heavy metals. The carbon is compressed into a solid block with uniform pore structure. Big Blue carbon blocks are available in both 10-inch and 20-inch sizes with micron ratings from 0.5 to 10 microns. They are essential for improving taste in drinking water and as pre-treatment before RO membranes to remove chlorine that would otherwise damage the membrane polymer.
Unlike carbon block, GAC cartridges contain loose granular carbon. They offer higher flow rates than carbon block of the same micron rating but less consistent contact with the water. GAC is often used for general taste and odor improvement where high flow is the priority. Some applicators use GAC cartridges in the first stage followed by a carbon block in the second stage for a balance of flow and performance.
Big Blue housings can also accommodate catalytic carbon for chloramine removal, KDF media for heavy metal reduction, ion exchange resin for hardness reduction, and phosphate cartridges for scale inhibition. There are also hybrid cartridges that combine sediment reduction with carbon filtration in a single unit, though these generally compromise on both functions compared to dedicated cartridges.
Flow rate capacity depends on several factors: housing size, cartridge type, micron rating, and inlet water pressure. A general rule of thumb is that a 10-inch Big Blue with a standard sediment cartridge can handle 10-15 GPM, while the 20-inch version handles 20-30 GPM. However, these numbers assume adequate inlet pressure and clean cartridges.
When selecting a housing for a specific application, you should consider the peak flow rate your system needs to deliver. For a typical residential whole-house system, you need about 6-8 GPM to run two showers simultaneously plus a faucet. A single 10-inch Big Blue can handle this comfortably. For a commercial dishwasher requiring 3-4 GPM plus several sinks and faucets, a 20-inch housing or twin 10-inch housings configured in parallel may be more appropriate.
Operating multiple housings in parallel is a common way to increase total flow capacity. Two 10-inch Big Blue housings plumbed in parallel can deliver up to 25 GPM total, with the added benefit of redundancy. If one housing needs cartridge replacement, the other can continue operating while you service the first.
Pressure drop increases as the cartridge accumulates debris. A clean cartridge might have a pressure drop of 1-2 psi, while a heavily loaded cartridge could show 8-10 psi drop. The traditional recommendation is to replace cartridges when the pressure drop increases by 8-10 psi above the clean reading, or at a set time interval, whichever comes first. Installing pressure gauges before and after the housing makes this monitoring straightforward.
Big Blue housings serve a remarkably wide range of applications. Here are the most common ones and how to configure them properly.
This is the most widespread application. A Big Blue housing installed at the main water entry point removes sediment and sometimes chlorine before water reaches the rest of the household plumbing. A typical configuration uses a 20-micron pleated sediment cartridge. For municipal water that already has low sediment but contains chlorine, a GAC or carbon block cartridge provides both sediment reduction and chlorine removal. This protects water heaters, fixtures, and appliances from sediment buildup and chlorine degradation.
Large commercial RO systems almost always include Big Blue housings as part of the pre-treatment train. A typical setup uses one or two stages of sediment filtration followed by activated carbon. The sediment stage removes larger particles that could foul the RO membranes, while the carbon stage removes chlorine that would chemically attack the thin-film composite (TFC) polyamide membrane layer. Without this pre-treatment, RO membranes can fail in a matter of weeks rather than years.
Ice machines, coffee brewers, steamers, and dishwashers all benefit from filtered water. A 20-inch Big Blue with a scale-inhibiting cartridge is a common setup for ice machines and coffee equipment. The filtration protects expensive equipment from scale buildup, improves the taste of beverages, and reduces cleaning frequency. Many restaurant chains standardize on Big Blue housings across their locations for consistency and simplicity of maintenance.
In light industrial settings, Big Blue housings serve as guard filters before heat exchangers, cooling towers, boilers, and process equipment. They are also used in parts washing, surface finishing, and metal treatment lines where water quality affects product quality. The 20-inch or twin 20-inch configuration is standard for these applications because of the higher flow rates involved.
Replacement frequency depends on water quality and usage volume. There is no one-size-fits-all schedule, but here are general guidelines:
| Application | Cartridge Type | Typical Replacement Interval | Signs It Needs Changing |
|---|---|---|---|
| Municipal water, whole-house | Pleated sediment (20-50 micron) | 3-6 months | Visible discoloration, pressure drop >8 psi |
| Well water with sediment | Melt-blown sediment (5-20 micron) | 1-3 months | Brown water, reduced flow rate |
| Chlorine reduction | Carbon block (5-10 micron) | 6-12 months | Chlorine taste returning in water |
| Commercial kitchen | Scale-inhibitor or carbon | 3-6 months | Scale on equipment, change in water taste |
| RO pre-treatment | Sediment + carbon combination | 3-6 months | Declining RO production rate, increased pressure drop |
For most residential applications, starting with a 6-month replacement interval is reasonable. After the first change cycle, inspect the used cartridge. If it is heavily loaded with debris at 3 months, switch to a 3-month schedule. If it still looks relatively clean at 6 months, you can potentially extend to 9 or 12 months. The presence of seasonal changes in water quality can also affect scheduling. Many municipalities see higher turbidity during spring runoff or after heavy rainfall, which can load cartridges faster during those periods.
Standard polypropylene Big Blue housings are typically rated for 90-125 psi maximum working pressure at ambient temperature. High-temperature variants may have lower pressure ratings. For example, a standard PP housing rated at 125 psi at 75°F may drop to 75 psi at 120°F. This pressure-temperature derating is critical to understand when installing the housing on hot water lines or in areas that experience high ambient temperatures.
If your incoming water pressure exceeds 80 psi, you should install a pressure reducing valve (PRV) before the Big Blue housing. Even though the housing may be rated for 125 psi, operating at the high end of the pressure range puts more stress on the O-rings, threads, and housing material. Over time, this can lead to fatigue cracking, especially if the housing is cycled through periodic depressurization during cartridge changes.
Stainless steel Big Blue housings offer higher pressure ratings, typically 150-250 psi depending on the model. These are used in commercial and industrial applications where higher pressure or elevated temperature is present. The trade-off is significantly higher cost and weight, as well as the inability to see the cartridge condition through an opaque stainless steel wall.
All Jingze Water Big Blue housings are pressure tested at the factory before shipment. Each housing carries a pressure rating label and includes installation instructions with specific torque recommendations for the sump connection to prevent leaks and ensure safe operation.
Big Blue filter housings offer a versatile, cost-effective platform for a wide range of water filtration applications. Whether you need basic sediment removal for a home, comprehensive pre-treatment for an RO system, or protection for commercial kitchen equipment, the right combination of housing size and cartridge type makes all the difference. The 10-inch size covers most residential needs, while the 20-inch version handles higher flow commercial and industrial applications. Understanding your water quality, peak flow requirements, and pressure conditions will guide you toward the right configuration. Jingze Water supplies a full line of Big Blue housings and compatible cartridges to meet diverse requirements across residential, commercial, and industrial applications worldwide. Contact our technical team for assistance selecting the right system for your specific needs.