I can actually get a hose to one of them from my well and we don;t get some rain pretty quickly I'm afraid I'm going to be filling it like a swimming pool...hmm my well pumps 600gal every 3 hrs, this is going to get ugly.

I can actually get a hose to one of them from my well and we don;t get some rain pretty quickly I'm afraid I'm going to be filling it like a swimming pool...hmm my well pumps 600gal every 3 hrs, this is going to get ugly.

Don't do that. You will WASTE a lot of water. You will lose X percentage to absorption into the ground plus, and this is the real culprit, a lot to evaporation. Depending on the surface area of your tank, you could be out 10s of thousands of gallons per year, most of that during warmer months.

Back in 2008, the estimate for North Texas tanks was about 72" of loss per year. Say you have a medium-sized 70 foot diameter round tank. Assuming with slope is averages to being a 50 foot diameter. At 72" or 6 (not 5!) feet, that would give you a volume of 11781 cubic feet of evaporation over the year. Of course, most of that will be during the summer, right? In that volume, you are looking at 88801 gallons of loss over the year.

You can reduce your surface area and reduce your evaporation loss consideration. If you are going to use a hose, buy a 50 or 100 gallon metal tank with a flow valve (like on toilets). You will limit your evaporation considerably by having much less surface area, but still have plenty of water on demand.

We are watering about 40 head of cattle from one 50 gallon tank hooked to a water hose, plus whatever critters show up.

So take this 50 gallon tank. It has about 5 square feet of surface area. Assuming 72" of loss, you are looking at 30 cubic feet of loss which translates to 224.4 gallons. You might even have less because none is getting absorbed in the ground.

In other words, if you are resorting to using the hose, filling a stock tank is not efficient. You are likely better off supplementing with a small metal watering tank. Plus depending on your property and hose, you might be able to put the tank under a tree for shade, reduce evaporation and keep the water cooler for the cattle.