Texas Toilet Water Regulations 2026: State GPF Rules

What Is the Texas Toilet GPF Limit and When Did It Take Effect?

Texas sits in one of the most water-stressed regions of North America. The state's population has grown by more than 4 million people since 2015, and the Edwards Aquifer, the Trinity Aquifer, and the Ogallala Aquifer face well-documented depletion pressures. Against that backdrop, the legislature acted decisively: toilets are the single largest indoor water user in a typical home, accounting for roughly 24 to 30 percent of total indoor water consumption according to EPA estimates. Cutting per-flush volume from 1.6 to 1.28 GPF represents a 20 percent reduction per flush -- significant at household scale and enormous when multiplied across 11 million Texas homes.

The law is codified in Texas Water Code, Chapter 372, originally enacted as House Bill 3169 (2011 session) and phased in over subsequent years. By the 2014 effective date for residential installations, retailers were also prohibited from selling non-compliant toilets for use in Texas. The TCEQ enforces the rule primarily through plumbing inspectors during the permit and inspection process.

Does the 1.28 GPF Rule Apply to Dual-Flush Toilets Differently?

The EFV formula matters because some early dual-flush designs used a 1.6 GPF full flush paired with a 0.8 GPF reduced flush, yielding an EFV of approximately 1.07 GPF. Those units can still comply mathematically under the EFV calculation, but Texas code inspectors generally expect the toilet to carry an EPA WaterSense label to speed approval without further verification. Models without that label may face additional scrutiny or a manual EFV calculation by the inspector.

If you are comparing dual-flush toilets for a Texas project, look for the WaterSense label first. Units from TOTO, Kohler, American Standard, Swiss Madison, and Woodbridge routinely carry this certification across their core product lines. Gerber's dual-flush Avalanche series and Niagara's Stealth also qualify. Avoid grey-market imports that carry unverifiable GPF claims; inspectors have the authority to fail an install if documentation is absent.

One important nuance in the table above: the American Standard Champion 4 in its classic 1.6 GPF configuration cannot be newly installed in Texas, yet it remains one of the most powerful gravity-flush toilets ever tested, with a MaP score of 1,000 grams. American Standard addressed this by introducing the Champion 4 Max, which drops to 1.28 GPF while maintaining an oversized 4-inch flush valve and 2-3/8-inch trapway. If you want Champion-level flush power with Texas compliance, the Champion 4 Max is the correct SKU to specify.

Which Texas Cities Have Water Rules Stricter Than the State Standard?

Understanding the difference between a mandate and a rebate incentive is important when planning a renovation. The state 1.28 GPF rule is a hard floor enforced at inspection. City rebate programs are voluntary programs that offset purchase costs when you exceed the state standard. Here is a summary of the major city programs as of June 2026:

• San Antonio (SAWS): Rebates of up to $100 per toilet for WaterSense-labeled models rated at 1.0 GPF or lower. SAWS has distributed rebates on more than 220,000 toilets since the program launched.
• Austin Water: Conservation rebates for single-family and multifamily accounts for WaterSense toilets. The rebate amount has varied between $50 and $75 per unit in recent cycles; check AustinWater.org for current figures before purchasing.
• Dallas Water Utilities: Toilet rebate program for residential customers replacing pre-1994 toilets with WaterSense models; rebates have ranged from $50 to $125 per toilet.
• El Paso Water: One of the longest-running rebate programs in Texas, targeting xeric landscaping and indoor efficiency simultaneously. El Paso's program favors 1.1 GPF or lower for maximum rebate tiers.
• Houston Public Works: Rebates are tied to the H-GAC (Houston-Galveston Area Council) regional water plan and vary by cycle. Customers in Houston are encouraged to contact HPW directly for current program status.

How Does MaP Testing Relate to Texas Water Efficiency Requirements?

The central concern with low-GPF mandates is flush performance. A toilet that uses 1.28 GPF but requires two flushes to clear waste uses 2.56 GPF per event -- worse than the 1.6 GPF toilets it replaced. MaP testing addresses this directly. The highest MaP rating, 1,000 grams, means the toilet cleared 1,000 grams of simulated waste in a single flush. For Texas households, a MaP score of 800 grams or higher is a widely accepted threshold for adequate performance; many plumbers and building engineers recommend 1,000 grams for primary bathrooms.

Texas-compliant toilets that also achieve 1,000-gram MaP scores include the TOTO Drake (MS776CSMFG), the TOTO UltraMax II (MS604114CEFG), the Kohler Cimarron (K-6418), the Kohler Highline (K-3998), the American Standard Cadet 3 (2383.128), and the Gerber Viper (GHE-21-318). All of these models flush at 1.28 GPF and have been independently verified to handle 1,000 grams in a single flush. For a broader comparison of high-performance options, see the guide to the best flushing toilets covering MaP scores, flush technology, and user-verified reliability.

Dual-flush models present a nuance: MaP scores are typically reported for the full-flush mode only, not the reduced flush. A toilet rated 800 grams on full flush and 0.8 GPF reduced flush may not reliably clear solid waste on the reduced mode. For Texas homeowners who want genuine water savings, selecting a dual-flush toilet where the full-flush mode still achieves 800 g or higher MaP is important -- the reduced flush is best reserved for liquid waste only.

What Penalties Apply for Installing a Non-Compliant Toilet in Texas?

Enforcement varies significantly by jurisdiction. In large Texas cities, building departments have active inspection programs and non-compliant installs rarely survive undetected during permitted renovations. In smaller municipalities or rural areas, enforcement can be lighter, but a non-compliant fixture will likely become an issue during a real estate transaction, since home inspectors and buyers' agents routinely check toilet GPF ratings against local code. Replacing a 1.6 GPF toilet before sale is increasingly a standard disclosure and negotiation item in Texas real estate transactions.

The practical consequence for homeowners is straightforward: always verify GPF before purchasing a toilet for any Texas installation. The product packaging, the EPA WaterSense label, and the manufacturer's specification sheet all display GPF clearly. If a deal on a toilet seems too good, check whether it is a 1.6 GPF model being cleared out of inventory -- those units are not legal for new installation in Texas regardless of price.

Homeowners who want to understand GPF compliance in a broader context, including how Texas rules compare to federal plumbing standards and other state laws, can review the detailed toilet GPF explained guide and the overview of high-efficiency toilet technology.

What Are the Best Texas-Compliant Toilets for High Flush Performance?

Below is a closer look at top-performing models that meet every Texas water law requirement:

TOTO Drake II (CST454CEFG)

The TOTO Drake II is the workhorse of the TOTO lineup and one of the most installed toilets in Texas for both residential and light commercial use. It flushes at 1.28 GPF using TOTO's Double Cyclone flushing technology, which generates two nozzle jets for full rim-and-bowl coverage rather than relying on traditional rim holes. The result is a MaP score of 1,000 grams verified through independent testing. The elongated bowl sits at comfort height (17 to 19 inches). The toilet carries EPA WaterSense certification and is among the most frequently specified models by Texas plumbers. The SoftClose seat can be added separately. Available as a two-piece unit, it ships in cartons that are easier to handle on job sites compared to one-piece alternatives.

For comparison between TOTO's key models, see the TOTO Drake vs Drake II comparison.

TOTO UltraMax II (MS604114CEFG)

The UltraMax II is TOTO's flagship one-piece toilet, offering the same 1.28 GPF Double Cyclone flush system as the Drake II in a seamless skirted-bottom design that simplifies cleaning. The one-piece construction eliminates the joint between tank and bowl that can be a leak point on two-piece units. MaP score is 1,000 grams. The elongated comfort-height bowl and CEFIONTECT glaze (which reduces waste adhesion to the porcelain surface) make this a top choice for primary bathrooms in Texas homes where water savings and low-maintenance cleaning are both priorities.

TOTO Aquia IV (CWT447247MFG)

The Aquia IV uses a dual-flush system (1.0 GPF full / 0.8 GPF reduced) and is WaterSense certified with an EFV well below 1.28 GPF. Its wall-hung configuration allows for adjustable bowl height and makes floor cleaning easy. For homeowners in Austin or San Antonio looking to maximize utility rebates while exceeding the state standard, the Aquia IV is a strong candidate. The 800-gram MaP score on full flush is adequate for most households, though not the 1,000-gram ceiling reached by the Drake II or UltraMax II.

Kohler Cimarron (K-6418)

The Kohler Cimarron uses Kohler's AquaPiston flush technology, which delivers water from a 360-degree angle into the bowl rather than from a single direction, reducing the risk of waste not clearing on the first flush. At 1.28 GPF with a 1,000-gram MaP score and EPA WaterSense certification, the Cimarron is fully Texas-compliant. The elongated comfort-height bowl and two-piece construction at a relatively accessible price point make it a popular choice for Texas builders managing budget constraints on large residential projects.

American Standard Cadet 3 (2383.128)

American Standard's Cadet 3 at 1.28 GPF is the entry point for homeowners who want the reliability of a legacy brand without the premium of TOTO or Kohler's upper-tier models. The Cadet 3 uses a large 3-inch flush valve and EverClean surface treatment to inhibit mold and bacteria growth on the bowl surface. MaP testing confirms 1,000-gram performance, and WaterSense certification is on the label. At 1.28 GPF, it is fully Texas-compliant. Note that the original Cadet 3 was sold in a 1.6 GPF configuration for many years -- always confirm the model number ends in ".128" to ensure GPF compliance.

Kohler Highline (K-3998)

The Kohler Highline is one of the longest-running toilet designs in American residential plumbing, and its 1.28 GPF variant (K-3998 or K-3999) continues to be a standard specification for Texas builders and remodelers. The AquaPiston canister valve provides strong flush performance, and the elongated comfort-height configuration is familiar to installers. A 1,000-gram MaP score and WaterSense label confirm both performance and compliance. For Texas rental properties where durability and parts availability matter, the Highline's long production history means replacement parts are universally stocked.

Gerber Viper (GHE-21-318)

Gerber does not receive as much consumer attention as TOTO or Kohler, but among Texas plumbers the Viper is respected for its reliability and 1,000-gram MaP score at 1.28 GPF. The Viper uses a 3-inch flush valve and a fully glazed trapway with a 2-1/8-inch minimum passageway. WaterSense certified. Gerber's commercial-grade build quality translates well to high-traffic residential bathrooms. The Viper is typically priced competitively, making it a practical choice for projects where multiple toilets need replacing simultaneously.

Woodbridge T-0001

The Woodbridge T-0001 has gained a following for its sleek modern appearance at an accessible price point. It is a dual-flush one-piece toilet (1.6 GPF full / 1.0 GPF reduced) with an EFV that qualifies under WaterSense and, therefore, Texas code. The full-flush volume at 1.6 GPF is above the state limit individually, but the WaterSense-certified EFV brings it into compliance. Homeowners should be aware that the full-flush mode exceeds 1.28 GPF individually; inspectors who are not familiar with the EFV rule occasionally flag this model. Carrying the WaterSense certificate documentation to the inspection resolves this quickly.

For more detailed specifications and owner feedback on the models above, see the separate reviews for the TOTO Drake II and Kohler Cimarron.

How Much Water and Money Can a Texas Household Save by Upgrading?

The EPA's WaterSense program publishes a household water savings calculator that accepts local water rates and flush frequency to produce personalized estimates. Texas homeowners can access this through the EPA WaterSense website (epa.gov/watersense) or through individual city utility sites that have embedded the calculator into their rebate application pages.

Payback period on a toilet upgrade depends heavily on water rates and whether a utility rebate applies. In San Antonio, where SAWS offers rebates and water rates are among the higher in Texas, a homeowner replacing two toilets can often recover the out-of-pocket cost within two to three years through combined rebate value and reduced water bills. In areas with lower water rates and no rebate program, the payback period can stretch to five to seven years, though the reduced risk of clogs and lower maintenance costs on modern low-flow designs add qualitative value that does not show up in a simple GPF calculation.

Homeowners interested in quantifying their specific savings can use the toilet water savings calculator to model different replacement scenarios based on household size, current GPF, and local water rates.