“What is the difference between static water level, groundwater depth and well depth?”
“Static water level“, “depth to groundwater” or (simply) “water level” are synonymous phrases that define the depth or distance from ground level to the level of water within the well.
When you are not presently pumping water and haven’t pumped recently, the meaning of “static” is the normal “resting” level of water. If you have pumped, then the water level is changing as the well fills back up to the static level. The “recovery rate” is the speed at which your well refills to the “static” level and is quoted in gallons per minute.
For example, your well may have a recovery rate of 3 gallons per minute. If you are using more than 3 gallons per minute, the level of water in your well is dropping. If you are using less, the level of water remains constant since the water is being replenished as fast as you are presently using it.
“Well depth” is defined as the entire drop, or drilled depth, of your well from ground level to the bottom of your well shaft. Usually the well has been drilled down into bedrock.
The difference between “static water level” and “well depth” is important because the static (resting) water level is the depth used to calculate the effort (usually measured in horsepower) required to pump water up to the surface. Regardless how deep the pump cylinder (or submersible pump) operates, the work required begins when the water in the pipe is lifted above the static water level in the well.
How deep the intake of the pump cylinder (or submersible pump) is below the water surface is basically irrelevant to the force needed because the (Simple Pump) sucker rods are so light. Therefore they add very little to the force needed. If you have measured your static water level every few months you will have noticed (sometimes significant) changes in the static water level. To accommodate for these natural groundwater (static) level movements we normally recommend the Simple Pump pump cylinder be installed at a depth 35-40 feet below the present static water level.
“How do I measure the depth to groundwater or static water level?”
Under the best of circumstances you have access to the well driller’s log filled out when the well was drilled. You can approximate the depth to groundwater from this information. If you don’t have the log, you can contact a local well driller or practicing engineer to have the water depth confirmed by sounding or other measurement techniques.
Please note: If you wish to determine your static water level yourself, you’ll need a small steel weight, a 1 + 1/4″ to 1 + 1/2″ diameter bobber and 200 feet of a lightweight fishing line or kite string.
- Attach the weight to the end of the line or string. At this time attach the bobber at least 1 inch above the weight.
- Carefully remove (or push aside) the well cap and lower the weighted end of the string/line into the well casing.
- When the bobber reaches the water level, the line will go limp. You’ll feel a slack in the line. You may also hear the water impact.
- At the point where you feel the slack, or hear the splash, mark the line at the top of the well casing. You may do so by tying a small knot in the line, placing tape at that point or even using a black marker. Just make sure the mark doesn’t move or disappear.
- Pull the line all the way back up and measure the length of the string/line from the weight/bobber to the marked line. This is your static water level.