COVID-19 has added some interesting discussions to our daily life. I received a phone call regarding the amount of water used to wash our hands for 20 seconds. It is fascinating how everyone now understands that 20 seconds is required for proper handwashing.

The question was, “Is a public faucet discharging 0.5 gpm enough water to properly wash your hands in 20 sec-onds?” The follow up to that was, “Do you realize that the plumbing codes classify employee-only lavatory faucets as public faucets?”

Let me answer the second question first. Yes, I am aware that the model plumbing codes have all changed in re-cent years, modifying employee fixtures by appearing to classify them as public fixtures.  The IAPMO National Standard Plumbing Code goes so far as to state that employee fixtures are public use fixtures.

Previously, some of the plumbing codes did not include employee fixtures in the definition of public fixtures. The thought process was that these fixtures are restricted to employees; therefore, they are not public fixtures.

The reason for stating, “It appears that employee fixtures are public,” is because the ICC International Plumbing Code still stipulates requirements for public and employee water closets. That would give an indication that employee water closets are not public fixtures. This can be translated into employee lavatories not being classified as public.

If employee lavatories are, in fact, classified as public fixtures, all of the model plumbing codes require the maxi-mum water use to be 0.5 gpm or 0.25 gallons per cycle. This leads to the first question, “Is a faucet discharging 0.5 gpm enough water for thorough washing of one’s hands?”

A little experiment

I had to answer the first question with, “I don’t know.”

When we lowered the water use for public lavatories to 0.5 gpm, there was no analysis as to whether a 20 second handwashing provided thorough cleaning of one’s hands. The issue was more related to water conservation, and the ability to still perform handwashing; proper cleansing during handwashing was never evaluated. 

This got the best of me. I was curious as to whether a 0.5 gpm lavatory flow rate was adequate. Fortunately, I de-signed the plumbing in my house to be somewhat of a test laboratory. There are three water closets, a 1.0 gpf, a 1.28 gpf and a 1.6 gpf. Similarly, with four lavatories, two have aerators rated for 2.0 gpm, one at 1.5 gpm and one at 0.5 gpm. 

I decided to experiment with the 1.5 gpm and 0.5 gpm lavatories. First, I tested the flow rate to see how close it was to the aerator rating. The 1.5 gpm lavatory flowed 1.5 gpm right on the money. The 0.5 gpm flowed 0.33 gpm.  Having lower water pressure in my house lowered the flow rate through the aerator. 

First, I thoroughly washed my hands using the 1.5 gpm lavatory faucet. It took me exactly 20 seconds to wash my hands in my normal manner. I was somewhat surprised that it timed out to exactly 20 seconds.

Then, I attempted to wash my hands using the 0.5 gpm lavatory. It took me longer to feel like I thoroughly cleaned my hands. It timed out at 35 seconds. However, even though all of the soap was off my hands, psychologically, I felt like there still might have been soap on my hands. It was all in my head — my hands were free of soap. I just wasn’t as comfortable as I was using the 1.5 gpm faucet.

What I learned is that you cannot properly wash your hands in 20 seconds using a flow rate of 0.33 gpm. I wish it flowed 0.5 gpm so I could do a proper comparison. But then again, there are many public faucets with 0.5 gpm aer-ators that are flowing only 0.33 gpm.

Lessons learned

What this simple experiment taught me is that you can thoroughly wash your hands at a lower flow rate faucet. However, it takes longer than 20 seconds. Had I not been using a stopwatch, I probably wouldn’t have known that I was washing my hands for 15 seconds longer than when I use the other faucet. Hence, it wasn’t inconvenient.

When I ran the numbers for the amount of water used during 20 seconds of handwashing, using the 1.5 gpm fau-cet, 0.5 gallons of water was used to properly wash. The 35 second handwashing used just under 0.2 gallons of wa-ter, or 40% of the water used with the other faucet. In reverse, it required 2 1/2 times the amount of water using the 1.5 gpm faucet. If I had used a standard residential faucet flowing the allowable 2.2 gpm, I would have used more than 0.7 gallons of water in 20 seconds.

This experiment also taught me that, with a self-metering faucet, we may have a problem with the numbers. Most self-metering faucets flow for more than 10 seconds and less than 15 seconds. That means that you cannot do a 20 second handwashing. It would probably require two cycles to complete the proper handwashing. That would result in a discharge of 0.5 gpm, which is the same amount of water used for the 20 second handwashing with the faucet discharging 1.5 gpm.

There was one last test to run. I usually never turn on the lavatory faucet completely, so I attempted to open the 1.5 gpm faucet 50%, or 0.75 gpm. The best I could do was 0.8 gpm, or a little more than half open. When I washed my hands, it took 20 seconds and I felt like my hands were clean and free of soap.

Flowing 0.8 gpm for 20 seconds resulted in me using 0.27 gallons of water. If I could have gotten the faucet to ad-just to 0.75 gpm, the amount of water discharging would have been 0.25 gallons, the same amount  allowed for a metering faucet.

This got me thinking, should we be requiring metering faucets to operate for 20 seconds, plus or minus 5 seconds? Currently, the only cycle time is in the accessibility standard, ICC A117.1, with a minimum cycle time of 10 seconds.

Next, should we consider moving the flow rate for public lavatories from 0.5 gpm to 0.75 gpm? Finally, are we pe-nalizing employees, especially in the medical profession, by only providing lavatory faucets with a flow rate of 0.5 gpm?

My simple experiments should only be the start of a discussion in our profession. This topic needs fur-ther investigation, preferably sooner rather than later. COVID-19 has given us the impetus to determine what flow rate in a public faucet is really necessary for proper handwashing in 20 seconds.