In THEORY based on 2 MILLION POOLS
(if anyone knows the exact number of AG+IG pools in CA please reply in comments)
Here is the formula:
Length * Width * Average Depth * Multiplier = Gallons
Determine the Multiplier:
Rectangle, square, or free-form pool:multiplier = 7.5.
Round or Oval pool: multiplier = 5.9
So if in theory there were 2 million pools in CA and we average the aboveground and inground multiplier to 6.5; then average the pool size to say 12x26 and a depth of 5 feet (just a guess but probably realistic); then using the FORMULA: 12x26x5x6.5 = ~ 10,000 gallons of water per pool rounded down for easy calculation.
Now 2 million pools times 10 thousand gallons completely evaporating each year as a rate of pool water evaporation
20,000,000,000 gallons of water
is evaporating in CA alone...that's 20 BILLION GALLONS of preventable waste!
If a city water tank capacity is 3.5 million gallons then there are ~5,715 city water tanks being wasted in CA each and every year by uncovered swimming pools
Now then, water savings via the use of inexpensive buoyant pool covers is easy to calculate given the evaporation rates in inches published by the National Weather Bureau. (http://www.grow.arizona.edu/Grow--GrowResources.php?ResourceId=208
Once the problem with removal and handling these inexpensive covers has been solve (i.e. managing the covers in sections like pieces of a puzzle for odd-shaped pools) it is not equitable to neighbors without pools to watch their lawns dry up while neighbors with pools continue to waste water that could be prevented through use of pool covers.
Taxing those pools with a $50/year tax however provides some equity and those pool owners can recoup their costs via lower water and chemical costs, and the tax revenues can be used to hold down water rate hikes on the average user without pools.
Comments encouraged !!
Thank you, David Hoff