Answer: It is normal for trees and shrubs to go through a little transplant shock, especially when they are installed during the heat of mid-summer. I don't know with what force or volume the water was directed at your new shrubs so I can't comment on whether or not this is what caused the death of your shrubs. I do know that shrubs and trees need well draining soils and will usually get by with about one inch of water per week. If you don't think your plants are getting that much - or are getting too much, you can check the soil moisture by watering as usual, waiting 3-4 days and digging a hole near the roots of your plants. If the soil is still moist 3 inches beneath the surface, you won't need to water for 3-4 days; if the soil is dry 3 inches below the surface, it's time to water again. If the soil is soggy, it doesn't drain well, which can cause root rot.
I wouldn't dig the plants up to air dry the roots - this will only distress them further. If the soil is truly soggy (after testing as above), dig the plants and transplant them to an area where you can control the amount of water they receive. If your soil is clayey and not well draining at all, consider building raised beds in which to plant your shrubs.
Best wishes with your garden!
Q&A Library Searching Tips