On a commercial site that offers information about the costs of
showering, I found these useful figures:
"The calculator uses 7 cents /kwh [kilowatt hour] as the average cost
of electricity... Multiply by the "cost to heat one litre of water to
average showering temperature" factor ( 0.1313685 )...Usually the cost
of other water heating methods (LNG, propane...) are close to the cost
of electricity, when it comes to heating water...
The national average for shower head flow rates is 2.6426 gpm [gallons
Shower Smart Faucet
Here is a map, in pdf file format, which shows the average cost of
electricity at various places in the US:
Annual Average Cost of Electricity (Cents/kWh) for Residential
Customers of Sample Utilities
The most recent figure for average cost of electricity (found in many
locations on the Web) is 8.5 cents per kilowatt hour:
"National average: 8.5¢ per kWh"
South Central Public Power District
Using the information from the Shower Smart site (linked above), with
an updated cost of 8.5 cents per kilowatt hour, we can do the math:
Cost of electricity: $0.085 per kWh
"Cost to heat one litre of water to shower temp" factor: 0.1313685
This gives us a heating cost per liter of $0.011166325 (or a little
more than one cent).
How many liters of water are used in the average ten-minute shower?
The average shower uses 2.6426 gallons per minute. Since there are
3.785 liters in each gallon, this would be 10.0022 liters per minute,
or 100.022 liters in ten minutes.
100.022 liters, multiplied by the cost per liter of $0.011166325,
gives a final answer (rounded to the nearest cent) of $1.12 for the
average ten-minute shower. This represents about 13.18 kWh.
Search terms used:
"average cost" + "shower"
"cost of showers"
"cost of a shower"
"cost of heating water"
"cost of heating a gallon"
"cost of heating a liter"
"cost to heat a gallon"
"cost to heat a liter"
I hope this information is helpful. If anything is unclear, or if a
link does not function, please request clarification; I'll be glad to
offer further assistance before you rate my answer.