Single-Stage Big Blue Whole House System — 10″ × 4.5″, 1″ Ports

This page covers specifications, installation, routine filter changes, and the exact replacement parts that fit this model.

Stage count and cartridge width decide which filters fit. Getting either wrong means a cartridge that won’t go in.

• One Big Blue housing (this system) — takes a single 10″ × 4.5″ cartridge.
• Two Big Blue housings — that’s the dual-stage system. Go to that page →
• Three Big Blue housings — that’s the triple-stage system. Go to that page →
• Narrow housings (~2.5″) with 3/4″ ports — that’s a slim system and takes entirely different cartridges. Find your model →

Mounting, 1″ NPT connections, startup, and the filter-change procedure.

Open the manual →

• Cold main line, after the house shut-off, in a dry, level, freeze-protected spot out of direct sunlight.
• Check the IN/OUT markings on the cap before you plumb it in.
• Use 5–10 wraps of PTFE tape. Do not over-wrap or over-torque — that’s what cracks caps, even with brass inserts.
• Mount to a wood stud with the supplied screws; masonry or drywall needs anchors.

This system doesn’t include built-in shutoffs. A valve on the inlet and the outlet turns future filter changes into a five-minute job instead of shutting off water to the whole house. A bypass loop is better still. If your installer didn’t fit them, close your main house shutoff before every change.

Component	Typical interval	Change sooner if…
Filter cartridge SED5-10BB as shipped	6–12 months 3–6 on heavy sediment or well water	House-wide pressure loss — the classic clogged-sediment signal · visible discoloration on the cartridge
Housing O-ring	Inspect every change Replace every 12–24 months	Cracked, flattened, brittle, or weeping at the seam
Filter housing	3–4 years	Any crazing, hairline cracks, cloudiness, or a leak that a new O-ring doesn’t stop

Filter housings are under constant line pressure. Over years the plastic fatigues and can crack without warning — and a failed Big Blue housing on a 1″ main line releases water fast enough to flood a home.

Replace the housing every 3–4 years regardless of appearance, and immediately at any sign of crazing, cracking, or a persistent leak. Write your install date on the housing with a marker, or on the magnet, so the next change is easy to date.

The like-for-like replacement — the same cartridge your system shipped with. Melt-blown polypropylene; captures dirt, silt, sand, rust and scale particles.

Same 5-micron rating and same fit, but the pleated construction can be rinsed and reused rather than replaced. On water that loads the cartridge every few months, this usually pays for itself.

On a two- or three-stage system, sediment sits in front and protects everything behind it. On a single-stage system there is no “behind.” Putting a carbon or specialty cartridge in this housing means you no longer have sediment filtration at all.

That matters because unprotected media clogs with grit and reaches the end of its useful life early — often much sooner than its rated interval. Expect a shorter service life, and a pressure drop that arrives faster.

If you want both sediment control and carbon or specialty treatment, the honest answer is a two-housing system rather than a compromise cartridge in this one.

Cartridge	Best for	What it does
Sediment — the default for a single-stage system
Pleated Sediment — Washable SED5-PLT-10BB · 5 µm	Heavy sediment & well water	Traps dirt, silt, sand, and rust like the standard sediment filter, but can be rinsed and reused instead of replaced. The most sensible swap on this system — it keeps sediment protection while cutting your running cost.
Carbon — replaces sediment filtration entirely
Carbon Block CTO CTO-10BB · 10 µm	Everyday chlorine, taste & odor — best value	Activated carbon block. Reduces chlorine, the tastes and odors it causes, and many common VOCs. At 10 micron it also captures fine sediment — unlike the 25-micron catalytic cartridges below — which makes it the most balanced single-cartridge choice if you want chlorine reduction without giving up all particle filtration.
Premium Coconut Carbon Block CACB-10BB · 10 µm	Best taste polishing · longest carbon life	Extruded coconut-shell carbon block — denser media with a finer pore structure than standard CTO, which is what coconut carbon is prized for on taste and odor. Rated 6–12 months rather than 3–12, so it goes longer between changes. Also 10 micron, so it captures fine sediment as well.
Advanced Catalytic Carbon CAT-10BB · 25 µm · Centaur®	Chloraminated city water	Catalytic carbon made with Centaur® by Calgon. Standard carbon has limited effect on chloramine — this is the correct media if your utility disinfects with chloramine rather than free chlorine. Also helps reduce hydrogen sulfide. At 25 micron it does little for sediment.
Premium Catalytic + KDF-85 CATKDF85-10BB · 25 µm	Chloramine + H₂S + metals · longest life	Catalytic carbon blended with KDF-85. Covers what the catalytic cartridge does and adds heavy-metal reduction. The KDF component also inhibits bacterial growth in the media bed, so it typically runs longest of the carbon options — useful on a single-stage system where nothing is protecting it.
Specialty media — replaces sediment filtration entirely
Bone Char BC-10BB · 25 µm	Fluoride, heavy metals & arsenic	One of the few media that helps reduce fluoride under suitable conditions, alongside heavy metals and arsenic. It also handles chlorine, taste, and odor. Performance depends on contact time and water chemistry.
Iron Reduction + Softening Resin IRON-10BB	Clear-water iron & light softening	Softening resin that reduces dissolved iron, manganese, and some hardness — the usual fix for orange staining on well water. For clear-water (dissolved) iron only. If your water comes out already orange or rusty, the iron has oxidized and needs a backwashing iron system instead. Note that well water usually carries sediment, which this cartridge is not designed to catch.
Scale Inhibitor — Salt-Free SCALE-10BB	Limescale protection	Conditions hardness minerals so they’re less able to form scale in pipes, water heaters, and appliances. No salt, no drain, no backwashing. Important: this does not remove hardness minerals and is not a water softener. Your water will still test hard and still feel hard — the benefit is scale protection for your plumbing, not soft water.

The right choice depends on what’s actually in your water, and with a single housing the trade-offs are sharper than on a multi-stage system. A water test is the reliable way to decide — guessing usually costs more than testing.

Browse all Big Blue specialty cartridges →  ·
Send us your water report →  ·
Free basic testing in San Diego →

Part	Part number	Notes
Big Blue Housing	HOUSING10BB	1″ ports, brass inserts, pressure-release cap
Housing O-Ring	—	The seal between housing and cap — the usual cause of a leak
Housing Wrench	WR-10BB	Replacement for the one in the box · Big Blue size only
Single-Stage Mounting Bracket	[[BR-1-10BB]]	Steel wall bracket
1″ Connection Nipple	FT-UN-1W-R	With O-ring · two per system

What you’re seeing	Most likely cause
Water pressure has dropped through the house	A loaded cartridge. This is the normal end-of-life signal — change it. On heavy-sediment water this can happen at 3–6 months.
Leak where the housing meets the cap	O-ring not seated in its groove, or worn. Depressurize, reseat or replace the O-ring, lightly grease it.
Leak at a 1″ port connection	Too little PTFE tape, or the nipple O-ring is missing or pinched. Redo with 5–10 wraps. Do not over-torque — that cracks caps even with brass inserts.
Water weeping from the pressure-release button	Debris under the button seal, or a worn button. Depressurize and press it several times to clear it. If it keeps weeping, replace the housing.
Housing won’t unscrew	Pressure still in the housing, or it was overtightened last time. Confirm the water is off and you’ve pressed the release button, then use the Big Blue wrench.
Still tastes or smells of chlorine	Expected with the sediment cartridge fitted — sediment media doesn’t touch chlorine. Chlorine reduction needs a carbon cartridge, which on a single-stage system means giving up sediment filtration. See the note above.
The cartridge I bought doesn’t fit	Almost always a slim 10″×2.5″ cartridge bought by mistake. This system takes the wider 10″×4.5″ Big Blue size.
I received extra cartridges I can’t use	You’ve likely bought a 2- or 3-cartridge set meant for a multi-housing system. This one takes a single cartridge.
Water is still hard, or leaves scale	Expected. This is a filtration system, not a softener — it does not remove hardness minerals. A scale inhibitor cartridge protects plumbing but won’t soften the water.

Scope note: As shipped, this is a sediment filtration system — it reduces particulate, not chlorine, hardness, or dissolved minerals. It is not a certified microbiological purifier and is not a water softener. Do not use it to make microbiologically unsafe water safe to drink; on an untested well or under a boil-water advisory, treat your water accordingly first.

Please note: Filter life and reduction performance depend on your water chemistry, pressure, and usage, so results vary from home to home. This product is not certified to treat water of unknown quality and is not a substitute for testing your water. Descriptions use general, qualified language and are not health claims. When in doubt, test your water or ask us and we’ll help you build the right stack.