Modern toilets can save you a lot of money, and all thanks to the new flush technology. In the 1990s and earlier, it wasn’t unusual to see toilets that waste 4 gallons per flus, and in some cases even 7 gallons. But today toilets only use 1.28 or 1.6 gallons per flush (GPF).
While this sounds very good for your pocket, most will wonder if this will be enough to clean the toilet bowl efficiently. Will my new toilet flush as efficiently as the old one? And If so, which one should I get the 1.28 or 1.6 GPF?
Why do Toilets Use Less Water Today?
The new toilets with lower GPF were introduced in 1994 when American President George H.W. Bush signed the Environmental Protection Agency into law. This law says that toilets shouldn’t use more than 1.6 gallons per flush. Well…this is when manufacturers had to rethink their ideas and start working on new technology and methods to design toilets that not only will use less water but also work efficiently. 
In the beginning, manufacturers didn’t do a nice job, because people would need to flush more than one time to remove the waste. This meant they had to find a way to make it more efficient. And they did! They redesigned the bowls and added larger flush valves. So now even 1.28 GPF toilets are efficient.
Changes in Flushing Technology
There are a few different methods that toilets use to achieve effective flush, and here is how they work:
Siphoning – In the U.S. most residences have siphoning models. These are toilets when flushed, the water flows to the rim and to a jet near the bottom. The jet pushes the water up traps waste, and pulls it down into the drain.
Wash Down – these toilets are more common in Europe than in the U.S. These toilets flush water under the rim and then push the waste through the trap. But in most cases, the water will still seem dirty and discolored, which means a second flush will be needed.
Power-assisted flush – Inside the toilet tank is a vessel containing air and water compressed by the incoming water. So when the flush valve opens water gets propelled into the bowl at high velocity. These are very powerful toilets. They might even need just 1.0 GPF for efficient waste cleaning. However the one downside is that they are very loud, and that’s why not many homeowners choose them.
1.28 vs. 1.6 GPF Differences
The main difference between these two types of toilets is the water use per flush. The 1.28 GPF ones use 20% less water, and this means you can save thousands of gallons of water each year.
- Cost – 1.28 GPF toilets tend to be more expensive, but they are more efficient
- Flushing Power – 1.6 GPF toilets have just slightly more power because of the higher water volume. This can be useful if you have constant issues with clogging.
- Economical – even though 1.6 GPF toilets use 20% more water than the 1.28 GPF, both of them will save you water, well, compared to the 3.5 GPF models.
- Regulations – In some places, like drought-prone areas, 1.6 GPF may not be allowed, which makes 1.28 GPF the only option.
Comparing Two Toilet Flush Types (1.28 vs. 1.6)
| TOTO Ultramax II | American Standard Champion 4 | |
| GPF (gallons per flush) | 1.28 | 1.6 |
| Flushing System | Dynamax Tornado Flush | Champion 4 Flushing System |
| Flush Type | Single | Single |
| Style | One-Piece | One-Piece |
While very similar, the TOTO Ultramax II is more efficient, saving 0.32 gallons of water with each flush. In doing so, you will use 20% less water. You can save over $100 per year using a 1.28 GPF toilet over a 1.6 GPF model. With the Ultramax II, you can save both money and water without compromising performance.
But, in the end, choosing between the two will depend on your needs: if you are looking to cut water costs the 1.28 GPF toilet is the one for you. But if you look for more power then go for a 1.6 GPF toilet, though even modern 1.28 GPF performs well too.
Use caution when looking to purchase a 1.28 GPF toilet, as only the most popular brands (TOTO and American Standard) carry the most efficient models. Other manufacturers do not typically implement high-end flushing technologies, meaning you may need to utilize two flushes to eliminate all waste.
Frequently Asked Questions
How can I check my toilet’s GPF?
Check the year label on your toilet. Most manufacturer’s name labels appear behind the seat hinge on the bowl. But if you can see it lift the lid and check the inside back of the toilet. The stamp is usually stamped on the porcelain. Then depending on the year, you’ll know the GPF of your toilet. Here is the info you’ll need:
| Year toilet was manufactured | Gallons per Flush (GPF) |
| pre-1982 | 5-7 |
| 1982-1990 | 3-5 |
| 1990-1994 | 1.6-3.5 |
| 1994-present | 1.6 |
| ~2005-present | 1.28 HET (see note) |
Note: In the U.S., since 1999, NET has been available, but on a limited basis, but started to be more commonly available in 2005. Some manufacturers from NET, dual flushing, use 1.6 GPF. So the stamp may show 1.6 GPF even if the toilet is an HET.
Are 1.6 GPF Toilets Allowed in California?
1.6 GPF toilets are not available in California, due to the California Energy Commission. All units sold within the state must use 1.28 gallons of water per flush or less.
What’s the Highest GPF Toilet?
Most toilets today use up to 1.6 gallons per flush. However, some older models can use as much as 4 gallons or more, which leads to lots of money wasted at the end of the year, especially if you live in a large family.
Do High-Efficiency Toilets Save Money?
Yes – as discussed, by consuming 20% less water with each flush, you’ll save on your water bills every year. Further, depending on your location, you could be eligible for additional rebates through the EPA’s WaterSense program.
Final Verdict
1.28 GPF toilets have several advantages. If you are in the market for a quiet, eco-friendly toilet that uses a minimal amount of water without sacrificing performance, a 1.28 GPF model is an excellent choice.
If you are unable to find a 1.28 GPF model from a top brand (TOTO or American Standard), it may be worth considering a 1.6 GPF model if flush efficiency is not a priority for you.