1. Home Water Supply Basic Facts a Homeowner Needs to Know
46% of NH Population Served by Private Wells
520,000 People Served by 250,000 Wells
Basic Facts a Homeowner Needs to Know
1) What Type of Well?
2) How Much Water?
3) Is the Water Safe to Drink?

2. Well Database
No. Records in Well Database ,500 Wells Constructed Annually in NH ,000 to 6,000 Wells Constructed in ,000+
Well Type % Total Wells
1) Drilled in Bedrock
2) Constructed in Sand and Gravel
3) Dug Wells Constructed by Excavation < 1
Median Depth (ft)
Median Yield (gpm)
Deepest Well (ft)
Bedrock Wells
320 8
2,500
Windham Wells
405 10
Deepest Well Windham Deepest Gravel Well Cornish 100 gpm
No. Wells w/Depths Ranging from 1,000 to 2,500 ft ,600+
Windham Well Depths from 1,000 to 2,500 ft

3. Fractured Bedrock Aquifer
Median Depth to Bedrock is 19 feet Minimum Casing 10 feet into Competent Bedrock
Age of NH Rocks 470 Ma Ordovician to 175 Ma Jurassic
Windham Data
Berwick Formation
Age – Silurian Period about 425 MA
Median Depth to bedrock = 8 feet

4. Bedrock Well Construction

5. Air Rotary Drilling
New Rotary Rig $680,000 Water & Pipe Truck $210,000 Drill Rods and Hammers $75, Pickup Truck $48,000 Kabota $30,000 On-Site Equip $1.1 to 1.2 Million

6. Cable Tool Drilling Robert Carr Water Wells Commonly called “Pounder”
About 20 Cable Tool Drillers Licensed in NH
Drill Rates 20 to 30 feet per day

7. Setting Casing Minimum Depth - 20 feet 10 feet into Competent Bedrock
Driveshoe Required
Sealed to Bedrock
Competent Bedrock – Structurally sound, w/ min fractures, joints, partings, and faults and Chemical or Physical weathering.
10 feet into Competent Bedrock

8. Glacial Stratified Drift Aquifer
Gravel Wells
Pleistocene Epoch 1,600,000 years to 10,000 years

9. Dug Wells

12. Lincoln Well Depth 522 ft Yield 40 gpm

13. Compressed Air Test

14. No State Requirement for Minimum Well Yield
Recommended Minimum Capacity
600 Gallons within a 2 Hour Period at Least Once Per Day
Equal to:
5 Gallons Per Minute for 2 Hours

15. Minimum Capacity Table Supply 600 Gallons in 2 Hours
Sustained Well Yield [gpm]
Required Well Depth [ft]
0.5
400 1
360
1.5
320 2
280
2.5
240 3
200
3.5
160 4
120
4.5 80 5
---

16. Well Yields for Domestic Bedrock Wells
Yield Range [gpm]
Statewide
Percent of Total
Town of Windham
Greater than 5
60%
62%
Between 2.1 and 5
30%
19%
Between 0.5 and 2 9%
14%
Less than 0.5 1% 5%

17. Hydro-Fracturing
500 to 2,000 psi 50 gpm pump 1,500 to 2,000 gal pumped

18. Hydraulic Pressure
Median Increase 3.5 gpm Number of Wells 5, % Wells

19. Water Bearing Fracture
After Development
Before Frac <1/2 GPM w/ 400’ static After Frac 6 gpm at 125’ fracture
Photo taken during pumping test

20. Median Increases in Yield following Hydrofracturing – February 2001 Based on 1,089 wells

21. Wellhead Protection 8 to 12 Inches Above Ground Sealed Cover
Screened Vent
Electrical Conduit Secured to Cover
Submersible Pump Ground Wire Bonded to Casing

22. Wire Connections & Grounding
Submersible pump motors grounded and bonded to well casings.
Wire connections must be water tight.
Exception:Grounding conductor
Wire nuts prohibited

23. Common Non-Compliant Cover

24. Electrical Conduit Not Secured

26. Busted!

27. Artesian Well
w/ Caulking Seal?
No Electrical Conduit?

28. Duct Tape!

29. Dug Wells Minimum 18 Inches Above Ground Surface
Dug Well with Access Plug

32. No Cover

33. Gruesome Discovery

34. Well Pits

35. Drinking Water and Groundwater Bureau at 271-3209
Well Information
Well Construction Details on the Web
Look for
OneStop Data and Information
Or Call
NH Geological Survey at or
Drinking Water and Groundwater Bureau at