Concern that a deep well can not provide adequate GPM using a CSV

[jamesEricAndy]

Since the CSV will control the pump to provide a constant pressure of 50 psi , it seems that a DEEP well will have a limited capability to provide sufficient GPM under a high load like running sprinklers while taking a shower, and running a clothes washer. We were told when we bought our 60 year old house that the shallow well failed and was replaced by a "deep" well, but have no idea how "deep" it is.
    How can I determine the max GPM the "deep" well is capable of providing, and how many GPM would be required to provide water to a single sprinkler, shower, and washer at the same time?
   Thanks

[Cary Austin]

A deep well must provide adequate flow, CSV or not.  Actually the CSV is easier on a weak producing well than without a CSV.  With a CSV the pump is only drawing as much as you are using.  Without a CSV, the pump always puts out maximum flow until the pressure tank is full.  Many times the extra water produced that is going into a pressure tank is enough to suck the well dry.

The average shower is 3 GPM.  The average sprinkler is also about 3 GPM.  But those can be different.  The washer will use 5 gallons and quit, so it doesn't use nearly as much as a shower or sprinkler.

5 GPM is usually enough for a house.  10 GPM is a good margin of safety.