High-Efficiency Toilet Questions
- How did EPA set the specification for toilets?
- How was UNAR developed?
- How does the specification ensure that these toilets will perform as expected?
- How will EPA verify the testing?
- Are toilets that meet WaterSense specifications more expensive than other toilets?
- Will the installation of high-efficiency toilets lead to drainline and sewer problems due to the reduced water flows?
Back to Frequent Questions Home Page
How did EPA set the specification for toilets?
The specification is based on the widely accepted Uniform
North American Requirements (UNAR) (PDF) (16 pp, 2.6MB, About PDF)
for toilets and EPA industry and product research, in collaboration
with external stakeholders. The EPA specification sets the water
use level at 1.28 gallons per flush or less, includes design requirements,
and has a higher requirement for flush performance to ensure optimal
user satisfaction.
How was UNAR developed?
Uniform North American Requirements (UNAR) were developed by a collaboration of water utilities to establish a standard for toilets in rebate programs that would perform to customer expectations, save water and maintain water savings over the long term.
How does the specification ensure that these toilets will perform as expected?
The specification includes a performance requirement. A collaboration
of U.S. and Canadian water utilities developed a flush performance
test protocol called the Maximum
Performance (MaP) testto provide a uniform measure of toilet performance. Requirements
for this test protocol have been included in the high-efficiency
toilet specification.
How will EPA verify the testing?
Products will be independently certified by a third party to confirm that the product meets EPA criteria for efficiency and performance.
Are toilets that meet the WaterSense specification more expensive than other toilets?
No. MaP testing results have shown no correlation between price and performance. Prices for toilets can range from less than $100 to more than $1,000. Much of the variability in price is due to style, not functional design. Toilets that could potentially bear the WaterSense label are currently in the low to middle range of about $200. There is a lot of competitive pressure on manufacturers to lower prices; therefore, it can be expected that as more toilets become certified, the average price should fall.
Will the installation of high-efficiency toilets lead to drainline and sewer problems due to the reduced water flows?
Since the introduction of the 1.6 gallons per flush toilet in the early 1990s, questions have been raised about whether sufficient water exists to move solid wastes in the building drainlines and in the municipal sewer system. To date, there has been no evidence to show that waste transport problems occur because of the use of the original low-flow toilets. The introduction of high-efficiency toilets in the late 1990s precipitated the same concerns. As a result, a collaboration of water utilities sponsored a full laboratory study to address the issue. The drainline study, completed in 2004, concluded that high-efficiency toilets flushing with as little as 1 gallon provide sufficient water in residential applications to move the waste from the fixtures to the sewer.
With regard to municipal sewer lines, the transport of waste has not proven to be an issue of concern in those areas with a concentration of high-efficiency toilets. Supplementary wastewater flows from other end-uses are always sufficient to move solids through the system. Furthermore, some wastewater utilities are co-funding and sponsoring the toilet replacement programs and other water efficiency initiatives of the water utilities for the very purpose of reducing sewer flows to their treatment plants.
Looking for something a bit more technical?
Click here if you are part of the media, an educator, manufacturer, professional or promotional partner.
Helpline: (866) WTR-SENS (987-7367) | Contact Us | Office of Water
WaterSense, U.S. Environmental Protection Agency, Office of Wastewater Management (4204M), 1200 Pennsylvania Avenue, N.W.Washington, D.C. 20460