Toilet: The king of water efficiency?

By Winston Huff, CPD, LEED AP BD+C

Is the toilet still the king of water-efficiency programs, or is its reign about to end? For more than 40 years, reducing the amount of water used in a toilet has resulted in significant water savings for facilities and municipal water districts, but how long can the toilet continue to help cities save water? In the future, will the toilet be able to achieve the dramatic water reductions that are needed?

Toilet rebate programs

Many cities facing water challenges are responding by implementing toilet rebate programs. For example, earlier this year New York City announced a rebate program to replace approximately 800,000 3.5 gallon-per-flush (gpf) toilets with high-efficiency models.

Why did New York City start this program? The NYC Department of Environmental Protection (DEP) is responsible for providing safe drinking water to more than eight million people each day. Fortunately, the city’s water requires very little treating or pumping because it is collected in protected watersheds in the mountains of Upstate New York and is gravity fed to the city via a complex tunnel and aqueduct system. However, a portion of the Delaware Aqueduct Rondout-West Branch Tunnel is leaking and will have to be repaired. While this work is done, the flow of available water to the city will be drastically reduced.

In anticipation of the aqueduct being shut down, the New York City DEP has implemented a Water for the Future initiative to reduce the city’s overall water consumption by five percent by 2020; a major component of the initiative is the Toilet Replacement Program. Under the program, owners of residential buildings will receive a rebate toward the cost of high-efficiency toilets (1.28 gpf or less) that replace older, less efficient toilets. According to its website, the DEP estimates that the program will reduce water consumption by three percent over the next seven years. On an average day, the city uses approximately one billion gallons of water, so a three percent reduction would save 30 million gallons per day. The program is scheduled to begin in 2013, and the vouchers are expected to be valued around $125, which is intended to cover the cost of the new toilet.

The city estimates that in 2011 residential consumption was 75 gallons of water per person per day. Toilets represent about 28 percent of that total. Comparing these figures with other studies shows that New York City is pretty close in their estimates.

In this column in March 2012, I reported on a case study from the Sonoma County Water Agency called “High-Efficiency Plumbing Fixture Direct Install Water Savings Analysis” by Koeller and Company. Their data reported on the effect of replacing fixtures with water-efficient versions. In 2009–2010, the Sonoma County Water Agency in Northern California created and managed a water conservation program encompassing the replacement of older water-using fixtures and fixture fittings with new high-efficiency products in both domestic (residential) and nonresidential applications. Qualified, licensed plumbers were used to install all items, which included toilet fixtures, urinals, showerheads and faucet aerators.
One part of the study showed that when 3.5 gpf residential fixtures were replaced with 1.28 gpf versions, the average water savings was 41.8 gallons per toilet per day. The Sonoma study showed that replacing commercial fixtures can result in even greater savings.

New York City has a rich history of reducing water usage with a toilet rebate program. When the Clean Water Act lowered the required flow to 1.6 gpf toilets in the early 1990s, the city initiated a similar program, which ran from 1994 to 1997, replaced 1.3 million toilets and helped save 90 million gallons of water per day. Since then, the city has seen a decline in water usage by approximately 30 percent, even though the population has increased.

Some concern surrounds the use of low-flow fixtures, specifically that they will have to be flushed twice for every use, thus negating the water savings. However, MaP testing and WaterSense certification have made a difference in the industry. This testing has improved the performance of 1.28 gpf fixtures compared to the 1.6 gpf fixture of the 1990s. The New York City rebate program requires WaterSense-labeled fixtures to reduce the problems that may have occurred in the earlier programs before WaterSense was in existence.

Poticrete?

Replacing 800,000 toilets with high-efficiency toilets sounds like a good idea when considering water issues, but what about the solid waste issue? Disposing of this many porcelain fixtures will create a landfill issue.

In response to this problem, the city is developing a program to reuse the porcelain for foundations, road beds or pavement. This is not unusual; most cities realize that offering incentives without having a plan in place for old toilets can result in toilets sitting on the side of the road. For instance, Bellingham, Washington, makes what they call poticrete (a combination of potty and concrete) out of old porcelain fixtures. The fixtures are ground up and used as aggregate in sidewalk cement. Most major toilet manufacturers also have active programs to recycle old fixtures into new products.

Other benefits

While not mentioned in many of the toilet rebate programs, they can result in other benefits, such as decreased flow in municipal wastewater systems and small septic systems. Many cities are facing combined water and sewer system overflows; reducing the wastewater flows in these systems can decrease the instance of overflows.

Wastewater systems use large amounts of energy to pump and treat waste; New York City has reported that 17 percent of the greenhouse gas (GHG) emissions from city buildings is from water and wastewater systems. Thus, reducing the volume of water in water distribution systems and wastewater systems will also reduce the amount of energy used and GHG emissions produced by these systems.

In the early 1990s, New York City also expanded a program to install water meters in buildings. As in other cities, water rates were not based on usage but on a complex formula that could include the amount of building street frontage. The meter program and the toilet program were the major pieces of an overall water conservation effort that remains to this day.

While the toilet rebate may be “king” in water-efficiency programs now, in New York it is not alone. The water meter program is scheduled to be expanded to include more properties and to enable users to access their water usage data on a regular basis. Studies have shown that when customers reap the financial benefits of water savings, they are more likely to initiate water-saving programs in their buildings. The New York City DEP is also working on a leak notification program that will use information from the meters to proactively alert customers to potential water leaks on their property.

Although toilet rebates are more frequently becoming part of water conservation programs, when looking at total populations and the amount of water that is processed in water treatment facilities, U.S. cities still use more than 100 gallons per person per day. This is a significant amount compared to other cities around the world, so more needs to be done.

Winston Huff, CPD, LEED AP BD+C, is a project manager, plumbing fire protection designer and sustainable coordinator with Smith Seckman Reed Consulting Engineers in Nashville, Tenn. He serves as an ASPE representative on the ICC Green Construction, Energy and Water Code Development Committee and is on the U.S. Green Building Council’s Water Efficiency Technical Advisory Group. He was the founding editor of Life Support and Biosphere Science and has served as its editor-in-chief. He also is editor of Me Green You Green (megreenyougreen.com), a LEED credit databank.