Well Water Testing

The following is an outline given in response to questions about the acceptable amount of well water. There is no single, clear response, because there are many variables that must be considered. Notice the basic breakdown below:

Plains Horse Acreage   15 GPM
  Small Farm   15 GPM
    Raising animals 15 GPM
    Raising crops 15 GPM
  Large Farm   15 – 100 GPM
    Dry Land 15 GPM
    Irrigated 100 GPM
  House and Lot   10 GPM
Mountain     ½ – 10 GPM
  Ranch   5+ GPM
  Horse Acreage   3 – 10 GPM
  House and Lot   ½ – 10 GPM
Lifestyle Executive-House & Guest   15 GPM
  Family   1 – 5 GPM
    1 – 5 Members 1 GPM
    6 -12 Members 3 GPM
  Rental   2 – 5 GPM
    Family 1 – 5 GPM
    Student 2 – 5 GPM
  Cabin – Vacation   1 – 3 GPM

Variations in gallon per minute to satisfy peak demand = Storage + Minimum GPM Daily Replacement.

Example #1:

1440 minutes     =     1 day

1440 gallons       =     1 GPM

Well depth of 300 feet with 200 feet of water = 300 gallons storage                           

Under normal circumstances, a house of 6 people would use a maximum of 300 gallons in the a.m. 
hours and 300 gallons in the p.m. hours. Between 10 a.m. and 3 p.m. (5 hours) the well would produce 
300 gallons, giving adequate water for a 3-bedroom house. The regeneration rate is 1 GPM.


Example #2
Same well depth  =  300 feet
Same storage     =  300 gallons
Same # of people =  6

The only change is a regeneration rate of 1/2 GPM.

Obviously, in the first example, the amount of water available was precisely enough to satisfy the daily needs of the household. In the second example, however, the amount of water available is less than required.

You might say that this is an inadequate water well situation. However, it is not.

If you provide additional storage by deepening the well or installing a cistern or storage tank, the problem is solved with adequate water available daily.

For Example: 1/2GPM X 1440 minutes = 720 gallons/day
720 gallons regeneration, placed in a 1500-gallon cistern or tank will provide an even better situation than the higher producing well in the first example. Peak demands like parties and house-guests would be satisfied.

This also supplies the additional benefit of having water available for the rural fire department when they can draw 100 GPM from the cistern to douse a house fire.

Needless to say, our opinion is not alone on this matter, and the VA Appraisers and FHA have been in agreement with these statistics.

Other authorities have also contributed to our resources material. Fairbank Morse Water Systems Division of Colt Industries states that the average of 50 gallons per day, per person, is needed. We feel that this is conservative, and that 100 gallons per day, per person, is a maximum requirement. Other mortgage lenders advised that proper computation of 2 persons per bedroom should be a consideration when the house is sold or listed to evaluate the quantity of water needed.

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