Human Nature Of Water Conservation
Julius Ballanco, PE
One of the greatest researchers in this area of plumbing, Tom Konen, recently passed away. Tom was a research professor at Stevens Institute of Technology in Hoboken, N.J.
One of Tom's admired research projects is the queuing theory. "Queue" means to wait in line.
Hence, the queuing theory is the study of human nature in the use of toilet rooms when there is a line. I would often see Tom sitting outside toilet rooms during meetings or large gatherings. He would observe the action of people using the plumbing fixtures, and their response if there was too long a line.
The published data from Professor Konen helped modify the plumbing fixture requirements in all of the model plumbing codes. His data also helped to solve the potty parity problem at stadiums, arenas and large theaters.
Women can thank Tom for balancing the waiting time to use plumbing fixtures. While he admitted that the wait will not disappear, Tom Konen knew that we could balance out the wait in line between the male and female population.
When water conservation measures were first being considered, Tom was in the forefront. He would often question the environmental and water conservation enthusiasts about the data on the human nature side of water use. The response, in the beginning, was always the same, "Don't worry, the people will get used to it." The effort was strictly, "save water, save water, save water."
What I learned from Tom Konen was the need to study human nature in the use of plumbing fixtures. He would instruct on the importance of studying the way people use fixtures, the way they react, and the tolerance they have in using fixtures.
The initial method of conserving water was to lower the maximum flow rates for kitchen sinks, lavatories and showers to 2.5 gpm. These values must be periodically reviewed in an effort to further save water. Ignoring the shower, let me review the use of water from faucets.
Closer LookA few years ago, lavatories and kitchen sink flow rates were lowered to 2.2 gpm; however, this flow rate is measured at a pressure of 60 psi. If a flow restrictor is used, 2.5 gpm at 80 psi is equal to 2.2 gpm at 60 psi. Hence, there was no change to the standard flow-restrictor-type of aerator.
While all of the flow rates were equal, human nature in the use of these fixtures varied from one fixture to the next.
The flow rate of public lavatories was reduced to 0.5 gpm. This is perhaps the least enforced section of the federal requirements for water conservation. Some inspectors think that if you put in an electronic faucet, the aerator can be set at 2.2 gpm. Of course, that is not true. The law permits either a flow rate of 0.5 gpm or a cycle of 0.25 gallons of water.
Let's start with the public lavatory first. I expected the public to be opposed to a 0.5 gpm aerator. In my observations, the 0.5 gpm has been well accepted. The preferred flow pattern seems to be a straight stream as opposed to multiple small streams of water. People are not cursing the faucets, saying, "Give me more water!"
The greatest objections are to electronic faucets that are not properly set up. Watch people respond to an electronic faucet when the water doesn't turn on right away. They start moving their hands around, trying to encourage the faucet to turn on. Then they get frustrated and go to the next faucet, waiting for it to turn on. Not all of the manufacturers have reached the optimum performance of electronic faucets. Perhaps the human nature studies by certain manufacturers were not as complete as they should have been.
If you study the use of the kitchen faucet, you will find the human response to be interesting. A kitchen faucet is the most used faucet in the house. My observations have been that a kitchen faucet is often opened only to the extent necessary for the task at hand. The flow is adjusted to either low or high flow.
The most popular faucet is the pull-out spray faucet. When these faucets are properly used to wash dishes, a flow rate of 2.2 gpm is necessary. When the faucet is turned upside down after being pulled out, you need enough flow to wash the dish, pot or pan. People become quickly frustrated when the stream of water is inadequate to properly wash away soap film.
When pots, bottles or glasses are filled with water, the flow rate doesn't matter. The person using the kitchen faucet wants to fill the item as quickly as possible. Additionally, there is no waste in water, since all of the water is being collected in a vessel.
In other words, the best way to conserve water use in a kitchen faucet is to pay attention to how people use the kitchen faucet.
For example, when potatoes are peeled in the garbage disposal, some people leave the water on the entire time they are peeling the potatoes. Others will turn the water off while pealing, and turn it on when washing the potatoes after peeling. The latter saves a considerable amount of water. More water is saved by the behavior modification than by lowering the flow rate through the aerator.
In a bathroom, human nature is somewhat different. The lavatory's faucet is more likely to be turned full open or full closed. This is especially true with children. Again, this behavior can be modified. However, I have found that there is a greater savings of water if the flow rate is significantly lowered. Rather than a 2.2 gpm, I have been observing those using a 1-gpm lavatory aerator.
You may think that 1 gpm is an inadequate flow for a lavatory faucet. But, think of the function of the lavatory faucet. There is enough water to wash your hands and face, enough water to shave and enough water to brush your teeth.
The downside of the 1-gpm aerator is the wait in the early morning for hot water. This is a part of human nature that is truly interesting. Most people will simply turn on the hot water and wait for the water to get hot. They do not use the water for any other purpose. While you could start brushing your teeth with the cold water coming out of the hot water side, most people consider that gross. After all, the water was already heated.
Following this logic, it wouldn't matter what flow rate was used. The clean water is merely running down the drain until the hot water arrives. With a lower flow rate aerator, it simply takes a little longer.
As for the wait for hot water, I have observed that the higher-income bracket is less patient than the middle- and lower-income brackets. This is something to keep in mind when installing the hot water system. For higher-income homes or units, it is sometimes worthwhile to install a hot water recirculation line.
I am going to miss my friend Professor Tom Konen, but he left a legacy for us to follow. We need to study the human nature side of our profession. Start considering the human side of water conservation, and think about a change in aerators that you use on a lavatory faucet.