Well Static Water Level - 1 year later testing

Pettrix · Nov 19, 2017

I had my well drilled last year out in AZ and it has been 1 year so it was tested to see where the water level sits. Originally during drilling they said I hit static water at 218 feet. 1 year later the static is now at 205 feet. Here are the results:

Well Depth = 505 feet
Pump Depth = 485 feet
Static = 205 feet (originally 218 feet when drilled)
30 minutes of pumping @ 5GPM = Well level dropped to 225 feet
1 hour of pumping @ 5GPM = Well level continued to hold @ 225 feet
Recovery = 20 minutes to return back to 205 feet

They said the recovery was equal to the 5GPM they were pumping out so I would have to increase the pumping to 10GPM to see what happened next. I decided that it was good enough since my well is at 505 feet deep with the pump at 485 feet, so I have plenty of water and didn't need further testing.

Should I test it more or just leave it with the results I have?
Is it normal for the well static level to increase after 1 year with drilling a new well?
I assume the above shows the well is a good well, right?

4570Man · Nov 19, 2017

If it's worked for a year I'd leave good enough alone. What are you hoping to gain or change by more testing?

canoworms · Nov 20, 2017

Water well and contaim driller here.
As a rough measure you have 20 feet draw down at 5 GPM you will have 40 feet draw down at 10 GPM etc.
With what you have below SWL( sorry static water level) to the pump I would just sit back and have a beer instead.
SWL will change with recharge, be it by local rain fall or distant recharge to a semi confined aquifer.
~20 lpm(5gpm) seems very low? is that all you are pumping?
If you have access to the well you can dip it while it is running and check the flow rate with a bucket. This will give you a realistic draw down.
Hope that helps.

Cheers Ian

Pettrix · Nov 21, 2017

canoworms said:
Water well and contaim driller here.
As a rough measure you have 20 feet draw down at 5 GPM you will have 40 feet draw down at 10 GPM etc.
With what you have below SWL( sorry static water level) to the pump I would just sit back and have a beer instead.
SWL will change with recharge, be it by local rain fall or distant recharge to a semi confined aquifer.
~20 lpm(5gpm) seems very low? is that all you are pumping?
If you have access to the well you can dip it while it is running and check the flow rate with a bucket. This will give you a realistic draw down.
Hope that helps.

Cheers Ian

I was pumping 5 GPM as that what my hose bib could put out. I would have to connect to the frost free line which bypasses the smaller plumbing lines and goes straight to a 1" line. I know I can get 10-15 GPM from my frost free line.

Would my well be considered an average or above average well?

Egon · Nov 21, 2017

There are lots of folks that would just love to have that well.

Gotta remember atmospheric pressure makes small changes to the water level.

Firemanbuck82 · Nov 21, 2017

Pettrix said:
Would my well be considered an average or above average well?

Does 5-10 gpm meet your needs? Then it's fine. Yours would be a piss poor well in some areas and a boomer in others... Why put a label on it (average/above average)?

The specific yield of the well is calculated as gpm/foot of drawdown. While it would be nice if it were a linear relationship, it rarely is due to losses within the borehole and the pump. You didn't state what size the pump is (what is the output rating for the TDH (total dynamic head). If you put in a 5 or 10 gpm pump, you aren't going to get more out of the well.

Firemanbuck82 · Nov 21, 2017

Egon said:
Gotta remember atmospheric pressure makes small changes to the water level.

Only if the aquifer is confined, otherwise it does not.

Pettrix · Nov 22, 2017

Firemanbuck82 said:
The specific yield of the well is calculated as gpm/foot of drawdown. While it would be nice if it were a linear relationship, it rarely is due to losses within the borehole and the pump. You didn't state what size the pump is (what is the output rating for the TDH (total dynamic head). If you put in a 5 or 10 gpm pump, you aren't going to get more out of the well.

The pump is 3HP and puts out around 20 GPM max when pumping below 350 feet. Above that it can pump up to 25GPM according to the chart.