Well more on the cistern. I had checked the level a couple of days ago to make sure we weren't using too much water. We have had scattered rain showers for the last few days and I checked it again this morning and we have gained about a foot of water over the area of the main cistern in a couple of days which means we can top off the pool again and still have enough water to get by. The cistern is basically 12 foot by 30 foot, split into two 12 foot by 15 foot tanks, so an extra foot of water works out to about 2700 gallons of water added to the already three feet deep or 8100 gallons that was already in the cistern. So if we gained a foot in the cistern, which is bigger than the pool, and we need to add about four inches to the pool we should still be in good shape. See all that math in school turns out to be use full after all. By the way I did have to Google it to get the formula its (lengthXwidthXheight)X7.5=Gallons, if measured in feet. I like the nice round numbers. I was going to take a picture of the inside of our cistern but I thought this one was much more impressive.