I don't like it or the looks of it. The 4" PVC is a problem with a 4" submersible pump; they actually measure 3 and 7/8". That's a 1/16" clearance around it in the 4" casing. I would want a 5" or 6" casing.
I really don't like home made tank tees... and if you think about it, where the boiler drain valve is prevents fully draining the tank. And why he used like 2" PVC is beyond me!! It's 1 1/4"
The galvanized nipples and such the switch is set on is ridiculous! It will eventually rust closed and prevent the pump from coming on or to shut off late, or otherwise lag. So this should be what material?
And this running the pressure relief under the house.... does that actually mean any water dumps under house/cellar floor? If so that is way wrong IMO.
Now we go to quality, as in water quality. With 100 gpm recovery, that says the chance of contamination is way high.... and with a water table of only 5'!