So the front orchard is going to need water. I could have just run the irrigation hose to the back tanks, but noooo that would have been easy. Instead I chose to harvest more water off the front of the house where very little water is harvested. I already have two 55 gallon barrels taking in water on the front, those water the fig tree. They only catch a fraction of the rain from 1200 sq ft of roof surface during a rain. So I put in another rain downspout, and ran it under the sidewalk. The tank is a 330 gallon IBC tote, painted and with a shade cloth to mitigate algae growth.
The easy way to tunnel under a side walk is using a water hose with water going full blast and shove it under. It erodes out the dirt and I can reach under and pull out the rocks. Took 20 minutes to dig the trenches on each side of the sidewalk but only took 10 minutes to burrow under. So the premise is the water will fill up the pipe, go down, then go back up the pipe and fill into the tank because the tank level is lower than the starting downspout level.
Then it rained a week later, the tank filled up and then overflowed, because I forgot to drill anti siphon holes on the top of the overflow U, the entire tank drained out. But I discovered that at the end of the rain and fixed it, so the tank filled 1/2 full before the end.
The front orchard has 8 trees in it: 2 Texas Persimmons (at least 40 years old), 2 jujubes, 2 Pomgranates, and a VDB fig.