Direct answer: The Watts WM100SM operating manual lists replacement parts for the W100 softener valve by Watts order number, all starting “KC11” or “KC12.” The most commonly needed are the motor (KC12V3107-01), PC board (KC12V3108), drive gears (KC12V3110), spacer stack (KC12V3005), downflow piston (KC12V3011), regenerant piston (KC12V3174), injector screen (KC12V3177), meter assembly (KC12V3003) and transformer (KC11V3186). The manual also sells the drive parts as one assembly, KC12V3002. Watts does not publish part prices; parts go through a Watts dealer.
Publisher boundary: Water System Guide is an independent research publisher, not a Watts dealer or parts seller. This page uses the Watts water conditioner operating manual with the WM100SM valve (FORM 0500-200, PDF created 2006) and the Watts Water Quality dealer catalog C-WQ-Dealer 2604 (April 2026), reviewed October 15, 2026. Order numbers come from the manual; confirm them with a Watts dealer before ordering, since the manual predates the current catalog.
Which Watts softeners these parts fit
The manual covers the “water conditioner with WM100SM valve,” listed as M3011-W100SM to M3021-W100SM (WM100SM manual, PDF page 4). The 2026 catalog sells current W100-valve models as M3011-CK10SM, M3013-CK10SM and M3015-CK10SM, and the dual-media M3011-W100SM-CR-CMP (dealer catalog, PDF pages 18 and 20). To order, read the full model number from the tank label, then give the dealer the order number and the color or number molded on the old part. Locksmith (L10SM, L125, L10T) and twin W100T systems use different valves, and this list does not apply to them. OneFlow systems use media kits instead; see our Watts OneFlow media replacement guide.
Front cover and drive assembly
From the manual’s drawing and part numbers (WM100SM manual, PDF page 18):
| Order no. | Description | Qty |
|---|---|---|
| KC11V317501 | W100SM front cover assembly | 1 |
| KC12V3107-01 | W100SM motor | 1 |
| KC12F3106-01 | W100SM drive bracket and spring clip | 1 |
| KC12V3108 | W100SM PC board | 1 |
| KC12V3110 | W100SM drive gear 12x36 | 3 |
| KC12V3109 | W100SM drive gear cover | 1 |
| KC12V3002 | W100SM drive assembly (parts 2 through 6) | — |
| KC11V3186 | W100SM transformer 110V-12V | 1 |
The manual says “drawing number parts 2 through 6 may be purchased as a complete assembly,” which covers the motor, bracket, board, gears and gear cover. These are the parts named in the error-code table for codes 1001 to 1004: a motor “not inserted fully to engage pinion,” a “drive gear label dirty or damaged,” a misaligned bracket or a defective board (WM100SM manual, PDF page 26). See our Watts error codes guide.
The manual’s component description explains the roles: “The drive bracket holds the PC board, the motor, the drive gears and the drive gear cover in place,” and “the PC board receives and retains information, displays the information, determines when to regenerate and initiates regeneration.”
Drive cap, pistons and spacer stack
The parts inside the valve body that direct water (WM100SM manual, PDF page 19):
| Order no. | Description |
|---|---|
| KC12V3005 | W100SM spacer stack assembly |
| KC12V3004 | Drive cap assembly |
| KC12V3135 | O-ring 228 |
| KC12V3011 | W100SM downflow piston assembly |
| KC12V3174 | W100SM regenerant piston |
| KC12V3180 | O-ring 337 |
The manual notes that “the regenerant piston is not used in backwash only applications.” Its troubleshooting table calls for these parts when the valve leaks internally (“change seals, spacers, and piston assembly”), when the drain flows continuously, or when there are “high drive forces on piston” (WM100SM manual, PDF pages 25 and 26). After any service on the drive cap or pistons, reset the valve by pressing NEXT and REGEN for 3 seconds.
Injector parts
The injector draws brine into the resin tank (WM100SM manual, PDF page 19):
| Order no. | Description |
|---|---|
| KC12V3176 | Injector cap |
| KC12V3152 | O-ring 135 |
| KC12V3177 | Injector screen |
| KC12V3010-12 | W100SM injector assembly, Z plug |
| KC12V3010-10 | W100SM injector assembly, D (red) |
| KC12V3010-1E | W100SM injector assembly, E (white) |
| KC12V3170 / KC12V3171 | O-rings 011 and 013 |
The manual says “the injector plug and the injector each contain one 011 (lower) and one 013 (upper) o-ring.” A plugged injector or injector screen is one of the listed causes of a softener that “fails to draw brine” or of hard water (WM100SM manual, PDF page 24). The injector is sized to the tank; see the color table below and match the existing color when replacing.
Refill and drain line flow controls
The refill flow control limits how fast the brine tank fills, and the drain line flow control (DLFC) sets the backwash rate (WM100SM manual, PDF page 20):
| Order no. | Description |
|---|---|
| KC12V3182 | W100SM refill flow control (RFC) |
| KC12V3165-01 | W100SM RFC retainer assembly |
| KC12V3195-01 | W100SM refill port plug assembly (backwash-only systems) |
| KC12V3158-01 | W100SM drain elbow 3/4” male assembly |
| KC12V3159-01 | W100SM DLFC retainer assembly |
| KC12V3162-022 | W100SM DLFC 2.2 gpm |
| KC12V3162-027 | W100SM DLFC 2.7 gpm |
| KC12V3163 | O-ring 019 |
The 2026 catalog lists backwash rates of 2.2 gpm for the M3011-CK10SM, 2.7 for the M3013 and 3.5 for the M3015 (dealer catalog, PDF page 20). A plugged drain line flow control appears in the manual’s troubleshooting for failure to draw brine and for excess water in the brine tank.
Injector and flow control sizes by tank
The manual’s component section gives two sizing tables (WM100SM manual, PDF page 13). Note that these tables use “KC11” prefixes where the drawing lists use “KC12” for the same parts; give the dealer both your model number and the color or number printed on the part.
| Injector part # | Color | Tank diameter |
|---|---|---|
| KC11V3010-1D | Red | 9” |
| KC11V3010-1E | White | 10” |
| KC11V3010-1F | Blue | 12” |
| KC11V3010-1G | Yellow | 13” |
| KC11V3010-1J | Light blue | 16” |
| KC11V3010-1K | Light green | 21” |
| Drain line flow control | Number on part | Backwash gpm |
|---|---|---|
| KC11V3162-022 | 22 | 2.2 |
| KC11V3162-027 | 27 | 2.7 |
| KC11V3162-03 | 32 | 3.2 |
| KC11V3162-053 | 53 | 5.3 |
| KC11V3162-075 | 75 | 7.5 |
| KC11V3190-110 | 110 | 11 |
The manual explains that the drain line flow control is “a flexible washer-like part” whose three-digit number “correspond[s] to the flow rate in gallons per minute,” and that the refill flow control “delivers a steady 0.5 gpm regenerant tank refill rate at varying inlet pressures.” It describes the meter turbine as “accurate to within ± 5%” from 0.25 gpm up to the valve’s maximum, and the bypass as having four positions, including “a diagnostic position that allows service personal to work on a pressurized system while still providing untreated bypass water.”
Meter
| Order no. | Description |
|---|---|
| KC12V3003 | W100SM meter assembly (includes turbine and O-ring 215) |
| KC12V3118-01 | W100SM turbine assembly |
| KC12V3105 | O-ring 215 |
| KC12V3003-01 | W100SM meter plug assembly |
| KC12V3151 | W100SM nut 1” quick connect |
The meter tells the valve how much water has been softened. The manual lists a “restricted/stalled meter turbine” or “defective meter” when there is no “softening” display while water flows, or when the valve regenerates only when REGEN is pressed (WM100SM manual, PDF page 21).
Bypass valve and fittings
From the bypass and installation fittings drawings (WM100SM manual, PDF pages 21 and 22):
| Order no. | Description |
|---|---|
| KC12V3145 | W100SM bypass 1” rotor |
| KC12V3146 | W100SM bypass cap |
| KC12V3147 | W100SM bypass handle |
| KC12V3148 | W100SM bypass rotor seal retainer |
| KC12V3150 | W100SM split ring |
| KC12V3149 | W100SM fitting, 1” PVC male NPT elbow |
| KC12V3189 | W100SM fitting, 3/4” and 1” PVC solvent 90 |
| KC12V3188 / KC12V3188-01 | W100SM fitting, 1” / 3/4” brass sweat |
| KC12V3193 | W100SM wrench |
The manual says the wrench is optional: “no tools are necessary to assemble or disassemble the valve.” It warns not to use “a pipe wrench to tighten or loosen nuts or caps” and not to use “Vaseline, oils, other hydrocarbon lubricants or spray silicone anywhere,” though “a silicon lubricant may be used on black o-rings” (WM100SM manual, PDF page 3).
Tanks and resin
The manual and catalog give tank sizes rather than part numbers. Current CK10SM systems use a 9 x 48, 10 x 54 or 12 x 52 mineral tank with 1, 1.5 or 2 cubic feet of resin, and an 18 x 36 brine tank with a “float valve to prevent brine overflow” (dealer catalog, PDF page 20). The dual-media M3011-W100SM-CR-CMP adds 0.5 cubic feet of coconut-shell carbon, and the catalog says “carbon can be replaced without replacing the resin” (dealer catalog, PDF page 18).
Warranty on parts
The manual’s warranty gives 5 years on fiberglass resin tanks, 5 years on the salt tank and control valve, and 1 year on component materials and workmanship. “Labor is not included. Warranty is limited to repair or replacement of defective part (manufacturer’s choice). Freight and shipping are not covered,” and returns need a Return Goods Authorization (WM100SM manual, PDF page 2). Check with the dealer before buying a part that may be covered.
Frequently asked questions
What is the part number for a Watts softener motor?
The WM100SM manual lists the W100SM motor as KC12V3107-01. The motor, drive bracket, PC board, drive gears and gear cover can also be bought together as the drive assembly, KC12V3002.
Where do I buy Watts softener parts?
Through a Watts dealer or branch. The 2026 catalog says Watts branches can take orders and quote prices. Use the KC order numbers from the manual and your model number when ordering.
Do these parts fit a Watts Locksmith softener?
No. The order numbers come from the WM100SM manual for W100-valve softeners. Locksmith systems use Watts’ own composite Locksmith valve, which has its own parts.
What part should I replace if my Watts softener will not draw brine?
The manual lists a plugged drain line flow control, injector or injector screen, low line pressure, or an internal control leak. Clean those parts first; the injector screen is KC12V3177.