Toto Home Additions & ADU Nationwide

Toto Home Additions & ADU: The Pomona Owner’s Guide

We stock and install Toto-compatible plumbing fixtures, toilets, and bidet systems for home additions and ADU projects in Pomona, with typical installed pricing from $450 to $2,800 per bathroom depending on the Toto series and rough-in configuration. Most Toto Washlet and Drake II orders arrive within 3-5 business days, and we schedule installation the day after delivery. Pomona homeowners usually discover a Toto part is failing when the bidet seat loses heating, the tornado flush weakens below 1.28 GPF, or the SoftClose hinge cracks after repeated use in a rental ADU.

Call (626) 606-1081

Which Toto Models This Applies To

Toto’s product lines split into three tiers that matter for additions and ADUs in Pomona. The Drake II and Ultramax II series use the Tornado Flush system with a 3-inch flush valve and Cefiontect glaze - the part numbers start CST454CEFG and MS604114CEFG respectively. The Washlet bidet seats (TCF6631U, TCF8012U) mount on most elongated Toto bowls but require a dedicated GFCI outlet within 3 feet of the water line, which we verify during rough-in inspection. The commercial-grade Eco Ultramax uses a different bolt pattern - 5.5 inches center-to-center versus 6 inches residential - and we’ve seen Pomona landlords order the wrong seat twice in the past year.

To identify your part, check the stamped model number inside the tank lid or on the seat hinge housing. The THU500S fill valve fits Drake and Entrada tanks but not the older Supreme line, which uses a 2-inch flush valve we no longer stock. For ADU rentals, we typically quote the TOTO OEM part against the Korky 528MP aftermarket equivalent - the Korky saves $18-$35 but carries a 5-year warranty versus Toto’s 10-year on the tank internals. Measure twice, then we can talk.

Signs Your Toto Home Additions & ADU Is Failing

• Weak or incomplete flush. The Tornado Flush depends on a clean 3-inch flush valve and unobstructed rim jets. In Pomona, where water hardness runs 180-220 PPM, calcium builds on the valve seat and reduces the siphon velocity below 1.28 GPF within 4-6 years.
• Bidet seat not heating or spraying. The Washlet’s instant heater draws 1,270 watts; if the GFCI trips repeatedly, the heating element has grounded out. We find this more often in ADUs where tenants unplug the unit to reset it rather than calling for service.
• SoftClose lid slams shut. The damper hinge contains silicone oil that degrades with UV exposure. South-facing ADU bathrooms in Pomona see this failure in 3-4 years versus 7-8 in shaded installations.
• Phantom running or tank refilling every 20 minutes. The THU500S fill valve uses a floating cup seal that hardens in chlorinated water. Pomona’s municipal supply runs 2.5-3.0 mg/L free chlorine, which accelerates this to a 5-7 year lifespan.
• Water pooling at the bowl base. The 2-inch wax ring compresses over time; in additions with post-tension slabs, minor settlement cracks the seal. We always inspect the flange level with a torpedo level before resetting - a 1/8-inch tilt guarantees recurrence.

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Replacement Cost & What’s Included

The range reflects three variables: whether the shutoff valve needs replacement (Pomona’s older homes near Garey Avenue still have 3/8-inch compression stops that won’t feed a modern fill valve), whether the flange sits below floor level and requires a spacer, and whether we pull the permit for an ADU rough-in. Under Clause 1 of the Haven Standard, the written price includes parts, labor, disposal, and the 365-Day Done Right Promise - no change order unless you sign it. We also source KraftMaid, Cambria, and Silestone for the full ADU build if you’re coordinating trades.

DIY or Call Us?

An owner can safely check three things before calling. Verify the water supply valve is fully open - quarter-turn ball valves fail closed more often than you’d expect. Clean the rim jets with a 3/32-inch drill bit held by hand, not a power tool. And confirm the Washlet plug hasn’t walked out of the GFCI receptacle behind the toilet.

Where DIY goes wrong: overtightening the tank-to-bowl bolts on a Drake II cracks the china at 35 inch-pounds, and there’s no torque spec stamped on the hardware. The fill valve height adjustment looks intuitive but sets the refill ratio for the bowl - wrong and you get weak flush or constant running. For Washlet electrical work, California Code requires GFCI protection within 36 inches of any water source; we’ve found homeowner installs in Pomona ADUs that skip this and void insurance. Call (626) 606-1081 and we’ll quote the repair in writing before anyone picks up a wrench.

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