Focus on the Flush with High-Efficiency Toilets

Creative plumbers can get an edge on the competition by matching flushing technology to household use
Focus on the Flush with High-Efficiency Toilets
Ed Del Grande

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When installing a residential high-efficiency toilet (HET), I believe plumbers should focus more on the toilet’s flushing technology. Also, how and where that flushing system can be used most effectively. Multiple HETs located in different areas of a home can operate efficiently using different flushing systems. This strategy can best serve the occupants and guests of that bathroom. Creative plumbers can get an edge over the competition by offering customized high-efficiency flushing technology for each bathroom.

Decades ago, when residential toilets used over 2 gallons per flush (gpf), not much thought went into the type of flushing system that would be used when installing a new toilet. For the most part, flapper-type flushing systems were the standard choice. But, with the disappointing performance of many 1.6 gpf toilets in the 1990s, it was obvious that new and improved flushing systems were needed. Since then, exciting changes in flushing technology have proven to be successful. This brings us to the modern-day HET.

Before I go into different types of HET flushing systems, let’s go over basic high-efficiency toilet requirements and what is considered a HET. As many plumbers know, the EPA WaterSense partnership program has specifications for HET water use set at 1.28 gallons per flush or less. This also includes design requirements and a higher requirement for flushing performance. Obviously this is less water per flush that the standard 1.6 gpf toilets on today’s market.

Basically, 1.28 gpf HET designers and manufacturers needed to figure out how to flush less water with power and an acceptable bowl rinse. It was not an easy task, but innovative design changes to dual-flush, assisted-flush and gravity-flushing systems have greatly improved HET performance. Also, it turns out that each new system has its own advantage. Let's take a closer look at these flushing advantages and how you can use different flushing systems to benefit the homeowner.

Here are three HET flushing systems I’ve chosen, why I like them and the bathrooms where you might want to install them:

1. Single-flush 1.28 gpf siphonic canister:

Single-flush gravity-siphonic toilets are easy to operate and have a good-sized water spot in the bowl. This type offers a wide variety of colors and styles to choose from. Plus, gravity toilets usually flush at lower noise levels since it’s a non-assisted flush. HETs with canister or aqua-piston technology deliver fast, smooth and consistent water flow from all sides of the tank opening. This helps maximize the flushing power of a 1.28 gpf HET. Single-flush canister systems are a good choice for bedroom areas that share a bathroom or a guest/child dedicated bathroom. With its quiet, easy-to-use operation, guests and children can enjoy a low stress bedtime and homeowners can enjoy lower water bills.

2. Dual-flush washdown:

Dual-flush washdown systems also are gravity-powered but without the siphon action. This system relies on the force of gravity alone to deliver its powerful pushing flush. All of the flushing water goes through the bowl rim, meaning you get a strong bowl rinse as well. The ability to choose your flush is how you achieve the water savings. With dual-flushing systems you can get a full 1.6-gallon flush or you can activate the water-saving, light-duty half-flush on demand. I like dual-flush toilets for master bathroom use. This way familiar users will most likely be operating the toilet, plus noise levels are low.

3. Single-flush air pressure-assist:

The big word here is “assist,” since air pressure is used to assist gravity and generate a very strong flush. The flush is so powerful that many residential air-assisted toilets flush with only 1 gallon of water. Air-pressurized flushing in most cases comes with a little extra noise. For that reason I like to use this type of flushing system in the more public bathrooms of the home, like a powder room. The extra power is more than welcome for higher traffic bathrooms.

For a video companion to this article, you can watch me demonstrate “smart” plumbing fixtures in a TV interview. Visit and click “Ed’s Bonus Banner” to view the bonus video below. 

About the Author: Ed Del Grande is a three-time master plumber, GBCI LEED green associate and contractor with licenses in pipefitting, fire protection and plumbing. He grew up in a family-owned plumbing business, and has 30-plus years of construction experience.

A self-employed contractor and professional comedian, he combined his performing and construction talents to become a pioneer in home-improvement television. Starting on HGTV with shows such as Dream Builders and The Fix, Del Grande helped build the DIY Network and with shows such as Warehouse Warriors and Ed The Plumber.


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