Tooth Brushing Math

Shutting off the water when brushing your teeth can significantly reduce water use over time. 

Water supplies are limited.

Unnecessary water use puts a burden on the environment.

Data sheet

Calculator

Pencil

Some way to set a timer

• Cell phone/or other timer applications

• Stop watch 

Water meter if available

Using the information on the data sheets determine how much water was used per toothbrushing and then try and determine an average based on the abilities of the group or individual.  This may mean that you eliminate fractions or decimals. 

Then start the discussion of how much water is actually needed to brush teeth for the 2 minutes recommended by the American Dental Association.

In fact it is less than .25 gallons or 1/4 gallon or 4 cups. Using the actual amount along with the the .25 gallons. that are necessary, the savings are remarkable.  

Using the one gallon per minute rate listed above, for 2 minutes, that is two gallons per brushing. 

The average person brushes at least 2x per day for a total of 4 gallons per day. 

The savings with shutting the water off when not necessary becomes about 3.75 gallons! When you multiply for 365 days the total is 1,368.75 gallons per person.  

This can be an exponential number by including members of a household, classroom, school, community. 

 Keep in mind that this would decrease the energy needed to make the water potable, travel to the residence where the brushing would take place, and the energy for the wastewater to be cleaned.  

It is important to recognize that even though the water goes down the drain clean when not in use, it still had to be ready for use at al times and it becomes dirty or unusable as soon as it hits the drain. 

Data may not be accurate if participants are not truthful

Not all faucets have GPM or gallons per minute stamped or printed on the fixture.  

• In this case 1.5 GPM is recommended as it is typically the maximum flow rate.  This can be modified to 1GPM for  younger participants.