Testing the Effect of Faucet Flowrate on Handwashing Efficacy

Handwashing is an important part of infection control, safety, and hygiene.

There are many factors that may determine the efficacy of handwashing, including:

  • the type of soap
  • the type of faucet
  • the length of handwashing time, and
  • the specific handwashing procedure

One factor that has not been examined in much detail is the potential effect of the water flowrate coming out of the faucet. The objective of this study was to examine the effect on handwashing of water flowrate from touchless faucets under laboratory-controlled conditions.

Over 21 participants were recruited to wash their hands using an established public health protocol and a non-antimicrobial soap. After washing, the participants’ hands were sampled to quantify the numbers of naturally occurring bacteria (resident flora) remaining on the skin.

A subset of six participants was subsequently used to test the effect of the highest and lowest flowrates on hands that were initially heavily contaminated with a non-pathogenic strain of Escherichia coli (E. coli), to examine the potential effects of water flowrate on non-resident flora.

Four laminar flow touchless faucets were used, pre-set at flowrates of 0.5, 1.0, 1.5, and 2.2 gallons per minute (gpm).

On average, approximately 300,000 microbes (5.5 log CFU) could be recovered from a participant’s hand after washing at any flowrate. Of those participants whose hands were initially contaminated with E. coli, handwashing removed 99.3% of the E. coli, confirming the importance of handwashing in contaminant removal. However, there was no statistically significant difference between the lowest (0.5
gmp) and highest (2.2 gpm) water flowrates used in the removal of E. coli.

It is concluded that faucet flowrate had no significant effect on handwashing efficacy under the specific conditions used in this testing.