Paper, Order, or Assignment Requirements
These figures are estimates. There is a tremendous amount of variation. For example, if you have
a water-efficient toilet the water used per flush will be as low as 1.5-2 gallons per flush. The amount of
water used for tooth brushing, shaving, hand and face washing, and dishwashing will vary significantly
based on the time spent and the faucet setting. The amount of water used on yard will vary depending on
the area in need of water.
- Calculate the water flowrate of your shower.
??Determine the flow rate of your shower head. (Time to fill a known volume)
Determine the flow rate (gpm: gallons per minute) of your shower head. Include a description of the method you
used and any calculations or conversions you used to determine the flow rate from your shower head.
Then determine how long it would take to recover the cost of a 2.5 gpm shower head based on the savings from
the reduced flow shower head compared to your existing shower head (find one and cite it from an online
source like a plumbing supply store or home improvement store).
- Use the data in the first table to fill in the “Estimated gallons per use or unit of time,” but
change the figures in that column if you have more accurate data about your personal water
- Create a PIE CHART (excel or similar programs) showing your own water use
Use Conditions Estimated gallons
Shower per minute *see above
Fill bathtub per use 30-50
Toilet Flushing per use (flush) 5
Tooth brushing per minute (letting water run) 3
Washing hands and face per minute (letting water run) 3
Shaving per minute (letting water run) 3
Cooking per meal 3
Washing Machine depends on setting 20-50
Dish Washing by hand (per minute) 3
Dish Washing w/machine (depends on setting) 15-30
Water Lawn per minute (depends on area) 10-20
Lawn Sprinklers per minute (depends on area) 5-20
Washing Car per minute 10
Wash down driveway w/hose per minute 10
Fill swimming pool per use 20,000-30,000
Personal Water Use Inventory
For shared activities like washing clothes, calculate your share of the water. For example, if
there are 4 people in your house/dorm room and the dish washing machine is estimated to use
30 gallons per load, your share is 30/4 = 7.5 gallons.
Refer to the website for the city of Flagstaff for the cost of water per gallon.
Number of Estimated Estimated Estimated
uses or time gallons per Cost per
Use gallons used gallons used cost per cost per
used per use or unit gallon
day of time per day per week week year