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Part 3: Lower-Flush Fixtures Can Save Water, But Be Aware Of Infrastructure Challenges
By Casey Laughman, Managing Editor
June 2014 -
One concern with lower-flush rate toilets and urinals is infrastructure, specifically the sanitary lines. In some cases, the slope — usually 2 percent for pipes 2 1⁄4 inches and smaller and 1 percent for 3- to 6-inch pipes — is not steep enough for the lower flush rates to clear the lines, says Clemente. To avoid this in new construction, specify that the sanitary lines have a minimum slope of 2 percent.
“All the piping was based on the higher flush rates,” so lower flush rates may lead to blockages in the lines, he says. “Yeah, you may save water, but you’re going to have a little problem on the other side with your sanitary lines as well.”
In retrofit applications, the fixture itself can often help mitigate the problem, Fedak says. New low-flow toilets are designed in many cases to increase the pressure of the water as it drains into the sanitary system, which prevents buildup in the lines. Older models, especially early-generation models, can be more problematic, so replacing an older low-flow fixture with a newer one may kill two birds with one stone.
And, says Fedak, if you’re not sure whether it could be a problem, test out models in one or two areas before committing to a major replacement.
“It does depend on the building and the plumbing within the building,” she says. “It’s a combination of testing them out to make sure they’re going to work and making sure you’re aware of the models of units that you’re purchasing to make sure you’re getting higher-quality versions.”
Another maintenance area to watch closely is the valves on toilets and urinals. Not only do they need to be replaced on schedule to perform properly, but the staff members doing the maintenance need to be sure they’re paying close attention to the replacement they’re installing, says Hoffman. Standard sizing on things such as flappers in tank-type toilets or flush valves in toilets and urinals makes it possible to install the wrong flow-rate valve.
“A .5 gallons per flush urinal flush valve will fit into any toilet flush valve,” Hoffman says. “Vice versa, if you have five-gallon flush toilets in your building, you can put the five-gallon flush diaphragm into a urinal and have a five-gallon flush urinal. I have seen those. By the way: You jump back when you flush.”
One way that water is different than energy is how much of a role building occupants play in conservation efforts. While occupants may have some individual control over HVAC or lighting in their area, the bulk of the usage is going to be regulated by facilities staff and controls. With water, much of the usage is determined by occupants; after all, a hotel that shuts the showers off after five minutes is going to get an awful lot of complaints.
Part 1: How To Maximize Your Water Efficiency Efforts
Part 2: Electronic Faucets, Aerators Can Help Meet Water Efficiency Goals
Part 4: Water Efficiency Requires Occupant Cooperation, Change Of Habits