How Deep is the Well?
How to measure water well depth.

How do we measure the depth of a water well?
- Use a string and weight to measure well depth
- How much water is in the well? How long will the water well last? What is the well recovery rate?
- Well Flow Rate, Well Yield, & Water Quantity Explained - Problems & Repair Advice for wells
- What are well static head, flow rate, and delivery quantity? How is well quantity measured?
Question & answers on the procedure to make the basic measurements of a water well: diameter, depth, water level, static head.
References

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How to measure well depth: this article series describes how we measure the depth of a water well. We caution that the amount of water available and the water delivery rate ability of various types of drinking water sources like wells, cisterns, dug wells, drilled wells, and even artesian wells is not answered just by measuring the depth of the well itself, but still we often need to know this number in order to know how to shock the well or how to prepare pipes, controls, and well pump choices or settings

How To Measure the Depth of a Water Well

The sketch at page top, courtesy of Carson Dunlop, outlines what happens during a well drawdown or well flow test procedure. Details are below. Readers of this document should also see Water Tank Types and before assuming that a water problem is due to the well itself, see Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost.

In a companion article, How to Test Well Water Quantity, we describe both valid and questionable ways people measure well yield, and we offer some simple steps any home owner or home buyer can take to check the adequacy of water pressure and water quantity at a building.

First you have to find the well. Second you need to know what kind of well is installed: driven point, drilled, or hand dug well, for example.

Two Key Questions to Ask About the Water Well

If you are purchasing a property served by a private well of any sort, here are the critical questions to ask about the well itself:

Where is the well located? Is the well on the property being purchased?
What kind of well is it: hand dug well, driven point well, drilled well, spring, stream, (these water source alternatives have implications for sanitation and water quantity as well as safety)

Watch out: Measurements like the well depth, well flow rate, well recovery rate are all useful, but taken by themselves some of these numbers can give a false reading about the basic question of how much water is in the well? What we really need to know is the total quantity of water that can be drawn from the well and the quality of that water: is it potable, hard (mineral laden), smelly, dirty, requiring treatment for any aesthetic or health-concern contaminant? See How Much Water is In the Well? and see How to Test Well Water Quantity.

How to Find the Depth of a Well - String and Weight Method

The Water Ace Pump Company offers this nice, simple well depth measurement procedure that works for drilled wells or hand dug wells. We have added some details.

Tie a small but heavy weight to the end of a piece of string (be sure there is enough string; some wells are very deep). Lower the weight into the well until it reaches the bottom.

Take up the slack and mark the string at ground level. Pull the weight out of the well and measure from the bottom of the weight to the ground level mark. This is the depth of your well.

For relatively shallow wells, 30' or less, we sometimes use a tape measure directly, but a weight on a string assures that the line used to make a measurement is absolutely straight, so more accurate.

Watch out: be careful putting anything into your well, that you don't send down a weight that gets hooked on pipes or valves in the well bottom. Use a small fishing weight or a rounded object and tie it carefully.

Watch out: this procedure is important for matching the well pump capacity to the physical depth of the well opening in the ground. But it does not tell us much about how much water is actually in the well. Except for artesian wells, the top of the water level in the well will virtually always be some depth lower than the top of the ground surface.

Matching Well Pump Capacity to Well Depth

Water Ace continues:

Subtract five feet from the depth of your well. This number should not exceed the maximum rated depth for your pump. If it does, it will greatly hinder or prevent the proper operation of the pump.

FYI the five foot deduction from the physical well depth used to estimate pump capacitu is assuming that the water pick-up end of your in-well piping will be held about five feet off of the physical bottom of the well. That's because placing the water pick-up too close to the very bottom of the well risks picking up silt and debris, clogging the foot valve, piping, and water pump.

Additional reading about water wells:

Static Head of Water in the Well explains the role of water stored in the well casing or cavity itself and shows how to determine that volume. More about measuring the actual depth of a well is at DEPTH of a WELL, HOW TO MEASURE.
Well Yield: Well Flow Rate - explains how well yield or well flow rates are measured, provides formulas, and an example of calculations
Total Quantity of Water Available - explains the true volume of water that is available from a given well, the role of the static head, the flow rate, the pumping rate, and factors that affect well life and changes in well yield.

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Question & answers on the procedure to make the basic measurements of a water well: diameter, depth, water level, static head. .

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Water Ace Jet Pump Installation Manual, instructions from Water Ace Pump Co., web search 08/28/2010, original source: http://www.waterace.com/pdf/R510%20R520%20and%20R100%20Jet%20Pumps%20Manual.pdf
Consumer hotline: 800-942-3343 - instructions for the installation and maintenance of
Water Ace shallow well pump Model R510 1/2 HP
Water Ace deep well pump Model R100 convertible 1HP and
Water Ace deep well jet pump Model R250 convertible 1/2 hp.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
  Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
  Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
  Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
  Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
Thanks to reader Alan Starkman, Oaxaca, Mexico, for discussing well flow rate calculations 2/17/2010.
Water Fact Sheet #3, Using Low-Yielding Wells [ copy on file as /water/Low_Yield_Wells_Penn_State.pdf ] - , Penn State College of Agricultural Sciences, Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf

When and How to Shock or Chlorinate a Well - Procedure for Shocking a Well to (temporarily or maybe longer) "Correct" Bacterial Contamination
- Water Requirements, Home & Outdoor Living
Drinking Water testing, contamination, correction - all topics
General water testing and corrective measure advice: contact your local health department.
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Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
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