Replacement Filters for the Whirlpool WHER12 / WHER18 Reverse Osmosis System
Whirlpool · Sears · Kenmore Reverse Osmosis
Replacement Filters for the Whirlpool WHER12 / WHER18 Reverse Osmosis System
Every filter your system needs — stage by stage — led by the complete set our customers buy most.
Also sold as: Whirlpool WHER12 · Whirlpool WHER18 · WHER12 · WHER18 · WHER-12 · WHER-18
✓ Best value — both filters + membrane
WHER12 / WHER18 filter set with membrane
$67.00
Two 10" × 2" carbon block filters (FXWF-1000) + one 50 GPD TFC membrane. Built for the Whirlpool WHER12 and WHER18.
🛒 Add the complete set to cartStocking up for the year? Annual kit: 4 carbon blocks + membrane — $75.00 · filters only — $45.00.
Filters by stage
Buy a set above, or replace stages individually below.
1
Carbon block filter (first canister)
10µm coconut carbon block · 10" × 2"
Filtrex FXWF-1000 — carbon block — $15.24
2
Carbon block filter (second canister)
Same cartridge as stage 1 · 10" × 2"
Filtrex FXWF-1000 — carbon block — $15.24
When to replace
🪣 Carbon block filters: every 6 months💧 RO membrane: every 2–3 years
✓ Fits Whirlpool WHER12 / WHER18 with 10" × 2" carbon block canisters — not sure? call (714) 541-6600.
ℹ️ Kenmore or Sears RO? Some were built on the same platform, but models vary. Compare your old filters to the sizes above, or call (714) 541-6600 with the model number.
Not sure this is your system? Use the Isopure Water Filter Finder → Match by system name, by the part number printed on your current filter, or by snapping a photo.
Whirlpool WHER12 / WHER18 filter FAQ
What filters does the Whirlpool WHER18 use?
Our WHER12 / WHER18 kits use two 10" × 2" carbon block filters and a 50 GPD TFC membrane. Both canisters take the same carbon block (Filtrex FXWF-1000), so you buy two. The WHER12 / WHER18 set has both filters and the membrane.
Do the WHER12 and WHER18 take the same filters?
Yes. Our WHER12 / WHER18 set and annual kit use the same carbon blocks and membrane for both models.
How often should I change WHER12 / WHER18 filters?
Change the carbon blocks about every 6 months (the FXWF-1000 is rated for 3,000 gallons or 6 months). The membrane usually lasts 2 to 3 years.
Will this kit fit my Kenmore or Sears reverse osmosis system?
Some Kenmore and Sears under-sink RO units were built on the same platform, but we have not confirmed a full Kenmore model list. Our kit uses 10" × 2" carbon blocks and a 1.8" × 10" membrane, so compare those sizes to your old filters. Not sure? Call (714) 541-6600 with your model number.
I need Kenmore 42-34377 or 42-34370 cartridges. Are these the same?
No. The 42-34377 / 42-34370 is a different, larger carbon block cartridge. We sell a compatible 3-pack.
All replacement filters by system · Whirlpool WHELJ1 whole-house · Whirlpool WHESFC / WHKF-DWHBB whole-house
Compatibility reference only. Photos of complete systems shown on this page are provided to help you identify your unit and confirm that our filters fit. All brand names, model numbers, and product images are the property of their respective owners; Isopure Water (IPW Industries Inc.) is not affiliated with, sponsored by, or endorsed by these manufacturers. We sell compatible replacement filters and parts — not the branded systems pictured, unless a system is separately listed for sale on our store.
