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Reverse osmosis system with three filter housings, horizontal cartridge and white storage tank

Reverse osmosis system

Watts WP-4, WP4-50, KP-4, RO-4M RO Replacement Filters

This 4 stage RO system use sediment and carbon block pre-filters to reduce sediment, chlorine and chlorine by-products before the membrane filters out impurities larger than .001 microns. The carbon block post filter treats for taste and odor.

See the replacement schedule

Compatible parts

Everything that fits the Watts WP-4, WP4-50, KP-4, RO-4M

Ready Water RW-SED2510050 5-micron sediment filter, direct replacement for 93023 and PX05-9 7/8
Top Seller
Ready Water
Ready Water RW-SED2510050 Sediment Filter 5 Micron 2.5" x 10"
(92)
$8.99
Meets FDA requirements for food and beverage contact
Omnipure OMB934-5m 5-micron carbon block filter for standard 10-inch water filter housings
Omnipure
Omnipure OMB934-5m Carbon Block Filter 5 Micron 2.5" x 10"
(84)
$14.99
Reduces chlorine, taste and odor
NSF Certified performance
USA made compression molded
2.5" Drop-in carbon block element
AXEON TF - 1812 - 35 Reverse Osmosis Membrane 36 GPD, 200358 200358 - ESP Water
AXEON
AXEON TF-1812-35 Reverse Osmosis Membrane 36 GPD, 200358
(3)
$43.49
AXEON TF-1812-25 25 GPD thin-film composite reverse osmosis membrane, part 200357
AXEON
AXEON TF-1812-25 Reverse Osmosis Membrane 25 GPD, 200357
(20)
$37.49
Thin Film Composite (TFC)
NSF 58 Certified

Replacement filter info

Your replacement schedule

Each stage of the Watts WP-4, WP4-50, KP-4, RO-4M, the exact part that fits it, and when to change it.

  1. Stage 1: Sediment filter

    Part RW-SED2510050, Ready Water RW-SED2510050 Sediment Filter 5 Micron 2.5" x 10" $8.99

    Every 6–12 months

  2. Stage 2: Carbon block filter

    Part OMB934-5m, Omnipure OMB934-5m Carbon Block Filter 5 Micron 2.5" x 10" $14.99

    Every 6–12 months

  3. Stage 3: RO membrane

    Part 200358, AXEON TF-1812-35 Reverse Osmosis Membrane 36 GPD, 200358 $43.49

    Every 2 years

  4. Alternative for stage 3: RO membrane

    Part 200357, AXEON TF-1812-25 Reverse Osmosis Membrane 25 GPD, 200357 $37.49

    Every 2 years

  5. Stage 4: Carbon block filter

    Part OMB934-5m, Omnipure OMB934-5m Carbon Block Filter 5 Micron 2.5" x 10" $14.99

    Every 6–12 months

Manuals & instructions

Manuals and guides

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