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The measurements to take before you buy, how modern 1.28-gallon toilets actually perform, and the real differences between one-piece and two-piece designs.
Buying a toilet sounds simple until you're standing in front of forty of them. Three things determine whether you'll be happy: the rough-in, the flush system, and the design. In that order.
The rough-in is the distance from the finished wall to the center of the closet bolts holding the toilet down. The standard is 12 inches; older homes in our area sometimes have 10-inch or 14-inch rough-ins. Buy a 12-inch toilet for a 10-inch rough-in and it simply won't fit. Measure before you shop — it's one tape-measure reading.
California law (AB 715) has required new toilets to use no more than 1.28 gallons per flush since 2014 — and any remodel that pulls a building permit requires bringing old fixtures up to standard. The good news: modern 1.28 GPF toilets are nothing like the weak first-generation low-flow units that gave the category a bad name in the 1990s. Look for a WaterSense label and a high MaP score (the industry's independent flush-performance test); a well-designed gravity toilet with a 3-inch flush valve and glazed trapway clears better today at 1.28 gallons than old toilets did at 3.5.
One honest caveat from decades in the field: flush performance also depends on your drain piping. Homes with old 6-inch cast iron waste lines move solids differently than modern 3-inch plastic — it's part of why early low-flow toilets struggled. If your low-flush toilet clogs constantly, the toilet may not be the problem. That's a diagnosis worth making before you buy anything.
A one-piece toilet molds tank and bowl together: easier to clean, no tank-to-bowl gasket to ever leak, sleeker look — and a higher price, plus it's heavy to handle during installation. A two-piece is cheaper, easier to carry in pieces, and if the tank ever cracks you can replace just the tank. Performance-wise, with the same flush system inside, they flush the same. This one is budget and looks, not plumbing.
"Comfort height" (17–19 inches, chair height) is easier on knees and required for ADA compliance in commercial settings — we install a lot of them for aging-in-place remodels. Elongated bowls are more comfortable; round bowls save a few inches in tight bathrooms.
Want to see the difference before you commit? Our Upland showroom has toilets on display and plumbers behind the counter. Our FAQ also covers common toilet problems — leaks at the base, tank sealing, and more.