Israeli inspectors sample the water at the site….twice a year.
That’s not very often. There are some fairly quick tests available these days for bacteria indicating fecal contamination, but I’ve not looked lately for them in the “Bible” of water analysis. At the least, the common tests take 24 hours of incubation, and they are relatively inexpensive.
Maybe there’s a market for some enterprising entrepreneurs to open a kiosk to sell coliform test kits to pilgrims, such as this one at Amazon.