Average water loss?


Well-known member
May 13, 2009
We lost about an inch this past week. It was super hot. I notice more loss when the cover is off...for obvious reasons. We keep our pool at 92 or above so at night we probably lose some due to evaporation.

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
This map shows annual pan evaporation rates across the country where it's around 55" in Illinois. That would be 0.15" per day, but evaporation is higher in the summer because the pool water is often heated and the air is usually drier. It also depends a lot on wind. I usually double the annual amount for a rough summer limit so that would be 0.3" per day, but actual amounts would usually be less than that.


LifeTime Supporter
May 4, 2011
With the intense heat I've been losing probably 1" per week. An average week is somewhere around 1/4-1/2".