Four Tips When Specifying High-Efficiency Toilets

Facility managers may have concerns that the lower flush volume of HETs will cause problems related to the drain line carry in their buildings, leading to clogs and other issues.

By Kevin Kennedy

Many building owners are interested in installing high-efficiency toilets (HETs) in their building to save water and reduce utility bills. However, many also express concerns with the drain line carry of these models. HETs are toilets that use 1.28 gallons of water or less to flush a toilet. This that has been made a standard since the EPAct of 1992 and these toilets are characterized as “ultra-low-flow” toilets.

drain line carry
Photo: Adobe Stock/bluraz

HETs are useful in many ways, but for those who own one or many properties, the real benefit to using HETs are the cost savings and tax breaks. The EPA estimates that water-efficient toilets can reduce water usage up to 60% every year, lowering monthly water costs significantly and saving more than 13,000 gallons of water annually per toilet. However, before these benefits send you running to your contractors, consider these four best practices to ensure a HET works with the plumbing system in your building.

1. Choose a HET with a Powerful Flush to Avoid Drain Line Carry Issues
Many plumbers, engineers, and architects have concerns that the lower flush volume of HETs might cause issues with the drain line carry due to their predecessors the Ultra-low-flow toilets (ULF). “Drain line carry” describes how far waste needs to travel to get from the toilet to the sewer. Because the ULF toilets in the 90s were not designed to optimize the lower amount of water, they historically caused drain lines to clog as well as other major issues with the drainage piping. But, thanks to advances in technology, HETs have been proven to be just as powerful as a less-efficient toilet, while meeting EPA standards.

While drain line carry has been a persistent concern among plumbing and building professionals, studies from the Plumbing Efficiency Research Coalition (PERC) show that drain line carry issues are more often caused by variables other than flush volume. Overall, PERC found that if the toilet has a powerful flush, the volume of the water wasn’t significant. In the PERC studies (Phases I and II), results showed that the slope and diameter of the pipe were more significant factors in how far the drain line carried the media than the toilet’s flush volume. Essentially, the size of the pipe and the pipe’s slope percentage (tested at 1% and 2%), and the type of media that was flushed were the major factors that caused clogs and plugs.

2. Get to Know your Pipes
Knowing your plumbing system can make a huge different in choosing a HET that is optimized for drain line carry. It’s estimated that buildings built prior to 1960 utilized cast iron piping over PVC. If your facility pipes are cast iron, you’ll get better results with a HET that has a higher flush volume of 1.28 GPF and offers a pressure-assisted flush. Because cast iron piping isn’t smooth on the inside, you need a toilet with a very powerful flush that will propel media down the drainpipe and push it past any rough patches. However, if the piping is PVC or ABS, which is smooth on the inside, and it’s a building with lower traffic, like a residential or multi-family property, you will want a toilet with 1. 28 GPF and gravity-assist technology or a 0.8 GPF with vacuum-assist technology. Both provide a powerful flush and can save as much as $60,000 a year in some multi-family properties.

3. Look for HETs with Industry Certifications and Testing
Unfortunately, not all toilets are created equally, so if you want those tax breaks and cost savings, there are a few things your HETs will need to have before you purchase. Look for pressure-assisted toilets that can be installed in buildings with high amounts of traffic or that are older. Choose toilets that have the Environmental Protection Agency’s (EPA) WaterSense® and/or the MaP® Premium certifications. The EPA’s WaterSense certification qualifies the toilet as water-efficient but also ensures that it can sufficiently clear media. MaP Premium certification is crucial for a high-traffic commercial building to avoid clogging problems.

4. Optimize Installation and Maintenance
Aside from choosing fixtures that fit your property’s specific needs and ensuring they meet the requirements listed above, there are several things you can do to optimize drain line carry and reduce maintenance headaches:

  • Ask the crew installing the toilets or plumbing to add some cleanout joints. These are joints with sections that branch off and have a piece at the end that you can unscrew to easily clean out any clogs.
  • Set up annual or bi-annual maintenance calls to catch any structural issues or potential clogs before they happen.
  • If you can, provide toilet paper with lower wet tensile strength. Toilet paper that is single ply and is loosely woven performs the best when tested for drain line carry.

With the right knowledge, and by following the advice above, you will be able to find a HET that can save water and money on utility bills and will not cause any drain line carry issues.

Kennedy is the Senior Engineering Product Manager with Niagara. Founded in 1977, Niagara is focused on saving the world’s water through everyday ingenuity without sacrificing performance. Kennedy has over 20 years of design experience in the plumbing industry and has helped Niagara excel its Stealth Technology and superiority in reducing waste. With his help, Niagara was one of the first toilet manufacturers to re-engineer the flush for a high-power, low-maintenance, no-waste toilet with Stealth Technology that saves customers money by reducing water while maintaining high performance.

Click here for more news items about Restrooms and Facility Management.