Single-Stage Whole House Water Filter System — 10″ × 2.5″, 3/4″ Port

This page covers both versions — they use the same housing, bracket, wrench, and cartridges. The only difference is whether a filter cartridge came in the box.

Specifications, installation, routine filter changes, and the exact replacement parts that fit this model.

Both use identical hardware, so it only matters for knowing what you started with:

• WHS-1S-1025 — came with a 5-micron sediment cartridge already fitted.
• WHS-1H-1025 — housing only. You chose your own cartridge, so check what’s actually in the housing before reordering.

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

• One slim housing (this system) — takes a single 10″ × 2.5″ cartridge.
• Two or three slim housings — that’s a multi-stage system needing a matching 2- or 3-cartridge set. Find your model →
• A wide housing (~4.5″) with a 1″ port — that’s the Big Blue version and takes entirely different cartridges. See the Big Blue single-stage →

Mounting, 3/4″ NPT connections, startup, and the cartridge-change procedure.

Open the manual →

• Install on the main cold-water line at the point of entry, after the main shut-off valve. A bypass loop lets you service the filter without shutting off the whole house.
• Mount the bracket to a wall stud with the included screws — the housing hangs from the bracket for easy access.
• Use PTFE tape on the 3/4″ NPT threads, and confirm the flow direction (in → out) marked on the cap.
• Cold water only. Do not install on a hot-water line, and keep the unit freeze-protected and out of direct sunlight.
• Professional installation is recommended if you’re not comfortable working on main-line plumbing.

Component	Typical interval	Change sooner if…
Filter cartridge 5 µm sediment as shipped	3–6 months Nearer 3 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 — a failed housing on a main line can 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 spun-polypropylene cartridge the WHS-1S-1025 shipped with. Captures dirt, sand, silt, rust flakes 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, it usually pays for itself — and it keeps sediment protection, which the carbon and specialty options below do not.

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 · 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-10 · 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 coarser catalytic cartridges — making it the least compromised way to get chlorine reduction from a single housing.
Coconut Shell Carbon Block HQCBC-10-5 · 5 µm	Best taste polishing · finest particle capture	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. At 5 micron it holds back the most particulate of any carbon option, so on a single-housing system it’s the closest thing to getting both jobs from one cartridge.
Advanced Catalytic Carbon CAT-10 · GAC-style	Chloraminated city water	Catalytic carbon. Standard carbon has limited effect on chloramine — this is the correct media if your utility disinfects with chloramine rather than free chlorine. Also helps with hydrogen sulfide (rotten-egg smell). Being granular, it does little for sediment.
Premium Catalytic + KDF-85 CATKDF85 · 3/4 lb KDF	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
Iron Reduction — Iron-Removal Resin IRON10	Clear-water iron staining	Iron-removal resin that reduces dissolved iron — the usual fix for orange staining in sinks, tubs, and laundry 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 too, which this cartridge is not designed to catch.
Scale & Corrosion Inhibitor SCALE10 · polyphosphate	Limescale & corrosion protection	Polyphosphate media that holds hardness minerals in suspension so they’re less able to form scale in pipes, water heaters, and appliances, and helps limit corrosion of metal plumbing. 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 protecting 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 10″×2.5″ specialty cartridges →  ·
Send us your water report →  ·
Free basic testing in San Diego →

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 a slim housing with heavy sediment this can happen within a few 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 3/4″ port connection	Too little PTFE tape on the threads, or over-torquing has stressed the port. Redo the tape; do not over-tighten.
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 relief button, then use the long-reach 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 Big Blue 10″×4.5″ cartridge bought by mistake. This system takes the narrower 10″×2.5″ slim 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: With the standard sediment cartridge, this system reduces particulate only — it is not a chlorine, taste, or chemical filter unless fitted with the appropriate cartridge. 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.