Gerber Avalanche Toilet Review
A research-based review of Gerber's Avalanche toilet line: two-piece 1.28 and 1.6 gpf models, round and elongated ErgoHeight bowls, the Avalanche CT and Elite variants, and what to verify before buying.
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Gerber’s Avalanche is a family of gravity-flush toilets that Gerber positions at the top of its performance range. The core models are two-piece toilets in 1.28 and 1.6 gallons-per-flush versions, with round-front or elongated bowls in standard or ErgoHeight (chair) height, built for 10- or 12-inch rough-ins. Gerber’s literature lists a 3-inch flush valve, a dual-fed siphon jet, a fully glazed 2-inch trapway and a 1,000-gram MaP result.
This is a research-based review built from Gerber’s 2023 Avalanche brochure and Gerber’s product listings. We have not physically tested any Avalanche toilet; our methodology page explains how we work.
Status as of November 2026: The Avalanche line is current. Gerber’s US site has an Avalanche collection page and product pages for the two-piece models listed below, plus the Avalanche CT one-piece and two-piece. Older Avalanche part numbers in the AV-21 and WS-21 style still circulate at retailers; their status varies, so check the exact number on Gerber’s site before buying.
The Avalanche lineup
Gerber’s 2023 brochure lists the two-piece Avalanche models below. Each “combo” number is a complete toilet made of the listed bowl and tank.
| Flush rate | Bowl | Rough-in | Combo number |
|---|---|---|---|
| 1.28 gpf | Elongated ErgoHeight | 10 in. | GWS31817 |
| 1.28 gpf | Elongated ErgoHeight | 12 in. | GWS31818 |
| 1.28 gpf | Elongated | 10 in. | GWS31810 |
| 1.28 gpf | Elongated | 12 in. | GWS31812 |
| 1.28 gpf | Round front ErgoHeight | 10 in. | GWS31800 |
| 1.28 gpf | Round front ErgoHeight | 12 in. | GWS31802 |
| 1.6 gpf | Elongated ErgoHeight | 12 in. | GAV31818 |
| 1.6 gpf | Elongated | 12 in. | GAV31812 |
| 1.6 gpf | Round front ErgoHeight | 12 in. | GAV31802 |
Avalanche CT and Elite
Two related versions extend the line. The Avalanche CT uses a concealed trapway, which hides the S-shaped channel behind smooth side walls; Gerber lists a 1.28 gpf, 12-in. rough-in, elongated ErgoHeight CT in one-piece (G0021019) and two-piece (G0020832) form. The Elite is a two-piece toilet that Gerber describes as powered by the Avalanche flushing platform with a simple concealed trapway; see our Elite WS-20-828 review.
Gerber Avalanche two-piece specifications
| Brand | Gerber |
|---|---|
| Model | Avalanche two-piece: GWS318xx (1.28 gpf), GAV318xx (1.6 gpf) |
| Bowl shape compatibility | Round front or elongated; standard or ErgoHeight |
| Seat material | Vitreous china |
| Heated seat | No |
| Bidet features | No |
| Water heating | 1.28 gpf (4.8 Lpf) or 1.6 gpf (6.0 Lpf), gravity |
| Warm-air dryer | No |
| Installation requirements | 10 or 12 in. rough-in (1.28 gpf); 12 in. (1.6 gpf) |
| Power requirements | None |
| Warranty | Unverified |
| Dimensions | Unverified |
What’s inside: the Avalanche hardware
Gerber’s brochure walks through the parts that make up the Avalanche flush. Here is what each one does in plain terms.
- Tank shape. Gerber says the tank is designed to maximize head pressure and flush speed. In a gravity toilet, the height of water in the tank is what drives the flush.
- 3-in. flush valve. A wider opening between tank and bowl lets water drop faster, which Gerber says increases suction for a stronger flush.
- Fluidmaster 400A fill valve. Gerber calls it best in class. Using a name-brand fill valve can make replacement parts easier to find years later.
- Rigid flapper. Gerber calls it corrosion resistant and says it seals tightly. A flapper that doesn’t seal is the most common cause of a running toilet.
- QuietClean dual rim jets. Two jets circulate water around the rim; Gerber says they clean better and make a softer-sounding flush.
- Dual-fed siphon jet. An extra-large jet at the bottom of the bowl pushes water into the trapway to start the siphon.
- 2-in. fully glazed trapway. Glazing the inside of the trapway reduces friction and helps waste pass.
- KeepClean glaze. A permanent glaze that Gerber says helps keep residue from sticking.
- Large footprint. Gerber says the oversized base covers old caulk lines and flooring marks from a previous toilet, handy in replacement jobs.
The brochure also lists a 1,000 g MaP result and 60 ft of drain-line carry. MaP is an independent bulk-removal test; Gerber reports the figure, and it is not a score from this site.
What we like
- Wide choice of round, elongated, standard and ErgoHeight bowls
- 10-in. rough-in options at 1.28 gpf
- Standard, widely available Fluidmaster 400A fill valve
- 3-in. flush valve and dual-fed siphon jet
- Manufacturer-listed 1,000 g MaP result
- Concealed-trapway CT and Elite versions if you want smoother sides
Things to consider
- Warranty terms not confirmed in Gerber sources we could access
- Seat inclusion not confirmed per model
- Standard models are not described as concealed-trapway, so expect more contours to clean
- 1.6 gpf versions use more water and may not meet some local rules
- Model numbering has changed over the years, which can confuse buyers
1.28 gpf or 1.6 gpf?
The federal limit for new toilets is 1.6 gpf, and EPA WaterSense-labeled toilets use 1.28 gpf or less, which the EPA says is 20 percent less water. For most homes, the 1.28 gpf Avalanche is the better pick: Gerber’s brochure cites its 1,000 g MaP result for the Avalanche line without splitting it by flush rate, and the 1.28 gpf models come in more shapes and in 10-in. rough-in versions.
The 1.6 gpf versions are there if a project specifically calls for them. If you are in a state or city with stricter flush-volume rules, check local code before ordering one. Our water-saving bathroom guide and water estimator can help you size the difference.
Installation and upkeep
A two-piece Avalanche installs like most gravity toilets: set the bowl on a new wax ring over the flange, bolt it down, mount the tank and connect the supply line. The large footprint helps hide marks left by the old toilet, but it also means you should check that the base sits flat on your floor before tightening anything. Overtightening the floor or tank bolts can crack vitreous china.
For upkeep, the parts most likely to need attention over the years are the flapper and fill valve. Gerber’s own care guidance warns that in-tank cleaners containing chlorine or bleach can void the warranty, so clean the bowl directly instead. If you are not comfortable with any of this, hire a licensed plumber.
Who it’s for
- Replacement jobs, thanks to the large footprint and 10- or 12-in. rough-in options.
- Households that want a familiar gravity toilet with common, replaceable parts rather than a pressure-assist tank or electronics.
- Taller users or anyone who prefers a higher seat. Gerber defines ErgoHeight bowls as about 16.5 in. or higher at the rim, versus about 14 to 16 in. for standard bowls. Read our chair height guide to decide.
- Small bathrooms that need a round-front bowl.
If you want the strongest possible flush for heavy use, look at Gerber’s pressure-assist Ultra Flush instead; see our Ultra Flush UL-20-318 review.
What to check before you buy
- Rough-in. Measure from the finished wall to the center of the floor bolts and match the 10- or 12-in. model.
- Exact model number. Make sure the bowl, tank and combo numbers match a current Gerber listing.
- Seat. Confirm whether one is included; budget for a round or elongated seat if not.
- Warranty. Gerber’s brochure points to the full warranty statements on gerber-us.com. Read the one for your model.
- WaterSense listing. If you are claiming a rebate, look up the model in EPA’s WaterSense product search.
Frequently asked questions
Is the Gerber Avalanche a pressure-assist toilet?
No. Avalanche models are gravity toilets with a tank, flush valve and flapper. Gerber’s pressure-assist line is called Ultra Flush.
What does “CT” mean on an Avalanche toilet?
CT stands for concealed trapway. The flush is the same idea, but the side of the bowl is a smooth wall instead of an exposed, curvy trapway, which is easier to clean.
Does Gerber make an Avalanche for a 10-inch rough-in?
Yes. Gerber’s brochure lists 1.28 gpf Avalanche two-piece models for 10-in. rough-ins in elongated, elongated ErgoHeight and round-front ErgoHeight versions.
Is the Avalanche still made?
Yes. As of November 2026, Gerber’s site lists current Avalanche two-piece and Avalanche CT models. Some older part numbers have been replaced, so verify the number you see at a retailer.
Bottom line
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