Average Well Depth by State

What does the average well depth by state evidence show?

The federal evidence supplies a strong national benchmark, but state databases differ in purpose, coverage, start date, location quality, and well-use classification. The fastest defensible summary is below; each line carries its measurement, population, year, and source so it can stand alone.

1. The overall median depth of domestic-supply wells was 142 feet (43.3 meters) in the conterminous United States in USGS Scientific Investigations Report 2021-5069, first posted November 18, 2021. — U.S. Geological Survey
2. The overall median depth of public-supply wells was 202 feet (61.6 meters) in the same 2021 USGS study, 60 feet deeper than the domestic-supply median. — U.S. Geological Survey
3. The USGS depth study compiled about 7.6 million well records: 600,922 from the National Water Information System, 66,540 from EPA's Safe Drinking Water Information System, 31,448 from a groundwater ambient monitoring dataset, 6,096,503 from individual state datasets, 96,885 from a national brackish-aquifer study, and 729,564 from a glacial-aquifer study. — U.S. Geological Survey, 2021
4. The median open interval was 21 feet for domestic-supply wells and 49 feet for public-supply wells in the 2021 USGS study. — U.S. Geological Survey
5. The USGS organized the national analysis into 288 hydrogeologic settings, created from 57 principal aquifers, 65 secondary hydrogeologic regions, and mapped overlying sediments. — U.S. Geological Survey, 2021
6. Groundwater supplies 35 percent of drinking water in the United States, according to the 2021 USGS report. — U.S. Geological Survey
7. The United States Groundwater Well Database contains 14,260,752 standardized well records for wells constructed as far back as 1763 through 2023. — Lin, Miller, Waqar, and Marston, Scientific Data, published April 4, 2024
8. SynDWell-US contains 5,982,715 domestic-well records spanning 1680 through 2024 and was published by the USGS on January 14, 2026. — U.S. Geological Survey, DOI 10.5066/P13JP4JQ
9. The state-specific National Water-Well Database releases verified for this edition are Minnesota, published in December 2022; Michigan, published in December 2025; and Louisiana, published May 27, 2026. — U.S. Geological Survey
10. Michigan's official 2024 Wellogic construction summary reports an average well depth of 117 feet across 13,464 records submitted for that calendar year; 90 percent were classified as household wells. — Michigan Department of Environment, Great Lakes, and Energy
11. Among USGWD records that included a construction year, approximately 80 percent were constructed between 1975 and 2023, and the study reports that most contributing state databases began in the 1970s. — Lin and others, 2024
12. After the USGWD location-quality screen, the geospatial subset contained 1,094,995 California records and 81 New Hampshire records; these are study-specific usable-location counts, not current state inventory totals. — Lin and others, 2024
13. Only 20 states supplied an estimate of how completely their records represented wells in the state, and 19 states supplied no well-construction dates to USGWD. — Lin and others, 2024
14. USGWD excluded 1,915,978 records from its geospatial subset because of missing or incorrect locational details, while 1,421,235 records in the tabular database were flagged as potential duplicates rather than automatically deleted. — Lin and others, 2024
15. In 2015, 42.5 million people—about 13 percent of the U.S. population—were self-supplied for domestic water, and more than 98 percent of self-supplied domestic withdrawals came from fresh groundwater. — U.S. Geological Survey Circular 1441, published 2018

How deep is the average water well in the United States?

The overall median domestic-supply well depth in the conterminous United States was 142 feet, and the corresponding public-supply median was 202 feet, in USGS Scientific Investigations Report 2021-5069. Those are medians calculated from the compiled wells; the report separately used hydrogeologic-setting medians and moving-median methods to produce 1-square-kilometer grids of typical withdrawal-zone depths.

That distinction is the core data-integrity correction a writer needs before quoting the number. The national 142-foot figure is not an arithmetic mean, not a state average, not a water-table depth, and not itself a value read from one modeled grid cell.

The authors—James R. Degnan, Leon J. Kauffman, Melinda L. Erickson, Kenneth Belitz, and Paul E. Stackelberg—set out to support regional and national water-quality modeling. They compiled records from six sources:

• 600,922 records from the USGS National Water Information System;
• 66,540 from EPA's Safe Drinking Water Information System, primarily public-supply wells;
• 31,448 from a groundwater ambient monitoring dataset, primarily domestic-supply wells;
• 6,096,503 from individual state datasets;
• 96,885 from a national brackish-aquifer study; and
• 729,564 from a glacial-aquifer study.

The USGS then assigned wells to hydrogeologic settings. Fifty-seven principal aquifers and 65 secondary hydrogeologic regions were combined with mapped glacial sediment, coarse glacial sediment, and stream-valley alluvium to create 288 distinct settings. Medians for well depth and the top, bottom, and length of open intervals were calculated within those settings.

The report's spatial output is a set of grids at 1-square-kilometer resolution representing the approximate common—or “typical”—top, bottom, and length of domestic- and public-supply withdrawal zones. Where fewer than five wells occurred within a 100-kilometer radius, the study used moving medians and data from hydrogeologic settings with similar well-construction properties, geology, physiography, and topography.

Two results from that work deserve more attention than they usually receive.

The open interval is much shorter than total depth. The overall median open interval was 21 feet for domestic-supply wells and 49 feet for public-supply wells. The open interval is the screened or uncased portion connected to the aquifer; most of the borehole above it may be cased and sealed. Total well depth therefore does not, by itself, describe the interval through which water enters.

A deeper well is not automatically a better well. The USGS found the shallowest median bottom-of-open-interval depths for domestic wells in secondary hydrogeologic regions overlain by coarse glacial sediment. Depth records describe where wells were completed; they do not establish yield, water quality, or suitability by themselves.

Source: Degnan, J.R., Kauffman, L.J., Erickson, M.L., Belitz, K., and Stackelberg, P.E., 2021, Depth of groundwater used for drinking-water supplies in the United States: U.S. Geological Survey Scientific Investigations Report 2021-5069, 69 p., https://doi.org/10.3133/sir20215069. The associated data release is version 2.0, January 2026. Verified July 23, 2026.

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What does this index not claim?

The index is an original source map, not a completed 50-state depth calculation. It makes four boundaries explicit.

• It does not treat USGWD geospatial QA counts as current agency inventory totals. Those values are the records that remained usable for the study's location-based analysis after its source-specific collection dates and location checks.
• It does not assign an unverified reporting-start year. A database's earliest record, an enabling statute, and the year electronic filing began are different facts.
• It does not reproduce third-party 50-state averages whose well-use filters, denominators, date ranges, duplicate handling, and mean-versus-median method cannot be reconstructed from the published material.
• It does not publish a state median that this research team did not calculate. The reproducible protocol appears in Methodology.

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What does “well depth” mean?

Well depth is the total completed depth of the borehole below land surface. It is not the static water level, pumping water level, casing depth, pump setting, or the length of the open interval; these measurements can appear on the same completion report and answer different questions.

Florida's statewide form makes the separation visible. It has distinct fields for measured static water level, measured pumping water level, total well depth, cased depth, open-hole interval, screen interval, pump depth, and intake depth. The USGS 142-foot figure describes total well depth in the study's compiled domestic-supply records.

A sentence such as “the average well in this state is 200 feet deep” is a claim about a population of completed boreholes. A sentence such as “water begins at 200 feet” is a claim about groundwater occurrence. One cannot be substituted for the other.

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What determines how deep a well has to be?

Well depth reflects the aquifer or water-bearing interval selected for the well, local geology, the intended use and required yield, water quality, construction requirements, and groundwater conditions at the site. A statewide value can summarize records, but it cannot replace the hydrogeologic and construction information for a particular property.

Depth and thickness of water-bearing units. A well completed in shallow permeable sediment can be much shallower than a well that must reach a deeper carbonate or fractured-rock aquifer. The 288-setting structure of the USGS national study exists because well depths vary by aquifer, lithology, and overlying sediment.

Materials above and within the aquifer. Well logs record geologic materials and their thicknesses because clay, sand, gravel, limestone, dolostone, and fractured rock affect where a well can be cased, screened, or left open.

Stacked aquifer systems. Several usable units can occur at different depths beneath the same area. Selection of a completion interval can depend on yield, water quality, local construction rules, and the purpose of the well. Polk County, Florida, is a direct example: the surficial, intermediate, and Floridan systems occur in vertical sequence.

Intended use and withdrawal requirement. The USGS national data show a deeper overall median and a longer median open interval for public-supply wells than for domestic-supply wells.

Water quality at different depths. Deeper is not synonymous with safer. The USGS Ground Water Atlas reports that the intermediate aquifer system is the main source in Sarasota, Charlotte, and Lee Counties because the underlying Floridan aquifer system is deeply buried there and contains brackish or saltwater.

Naturally occurring constituents also vary by aquifer and groundwater age. A USGS study of untreated water from 1,676 domestic-supply wells and 1,464 public-supply wells found lithium above a nonregulatory 10-microgram-per-liter health-based screening level in 37 percent of domestic samples and 45 percent of public-supply samples. Those percentages are screening-level comparisons, not Safe Drinking Water Act violations.

Groundwater levels and construction era. Water levels can change seasonally and over longer periods, while reporting practices and construction standards also change. Mixing old and recent records without showing construction year can hide a real time trend or create one through reporting coverage alone.

Private domestic wells are not regulated under the federal Safe Drinking Water Act and, in most cases, not under state drinking-water laws that apply to public systems. Depth records do not establish potability.

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How do wells work in Florida and Polk County?

Florida administers well construction through five regional water management districts and delegated authorities rather than one uniform public record portal. Polk County is also split between two water management districts and is underlain by three principal hydrogeologic units whose thicknesses change substantially across the county.

How are Florida's well records organized?

Florida DEP manages the Water Well Construction Program in coordination with the Northwest Florida, Suwannee River, St. Johns River, Southwest Florida, and South Florida water management districts. Polk County lies partly in the Southwest Florida Water Management District and partly in the South Florida Water Management District.

The State of Florida Well Completion Report, DEP Form 62-532.900(2), provides a common data structure. It records: permit number and completion date; Florida Unique ID, county, section, township, range, latitude, and longitude; work type and intended well use; measured static and pumping water levels; total well depth and cased depth; open-hole and screen intervals; casing and sealing information; pump depth and intake depth; and a drill-cuttings log.

This edition does not publish a statewide Florida average because it did not assemble, normalize, and deduplicate the required district-level record population.

What lies beneath Polk County?

USGS Scientific Investigations Report 2006-5320, published in 2007, used data from about 300 geophysical and geologic logs to map Polk County's hydrogeology. The report identifies three principal units.

The surficial aquifer system. Its thickness ranges from several feet or less in the extreme northwestern county and along parts of the Peace River south of Bartow to more than 200 feet along the southern Lake Wales Ridge in eastern Polk County.

The intermediate confining unit and intermediate aquifer system. Its combined thickness ranges from less than 25 feet in the extreme northwestern county to more than 300 feet in southwestern Polk County.

The Floridan aquifer system. This thick sequence of permeable limestone and dolostone includes the Upper Floridan aquifer, a middle semiconfining unit, a middle confining unit, and the Lower Floridan aquifer. The USGS report states that the Upper Floridan aquifer provides most of the water required to meet demand in Polk County.

The 2007 report also gives a quantified use context: Polk County groundwater withdrawals in 2002 were about 285 million gallons per day, and nearly 95 percent came from the Floridan aquifer system. That is a withdrawal statistic, not a domestic-well count.

Why would one Polk County average hide important differences?

Aquifer thickness is not the same as completed well depth, but the mapped variation shows why a county mean would need a clear record population. A well in one part of Polk County can encounter a very different thickness of surficial or intermediate material from a well elsewhere in the county, and wells can be completed in different hydrogeologic units.

A county statistic can still be useful if it is calculated from a defined set of domestic completion reports and published with its median, mean, percentiles, record count, construction-year range, aquifer information where available, and district source. This edition does not publish that number because that calculation was not performed.

For Polk County well service, see Lakeland and Polk County service area and well repair and casing work.

Sources: Spechler, R.M., and Kroening, S.E., 2007, Hydrology of Polk County, Florida, USGS SIR 2006-5320, https://doi.org/10.3133/sir20065320; Florida DEP Water Well Contractor Licensing and Permitting; DEP Form 62-532.900(2). Verified July 23, 2026.

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What are the limitations of this page and its data?

The page answers the query with the strongest verified national statistic and an original state-source index, not a fabricated 50-state average table. Its limitations are visible because each one changes how a number should be interpreted.

• This edition does not publish 50 state averages. It has not run the record-level state calculation. The source index and protocol are published instead of values that cannot be reproduced.
• The 142-foot figure is an overall median, not an arithmetic mean. It is the overall median depth for all domestic-supply wells in the 2021 USGS study.
• The principal federal products cover the conterminous United States. SIR 2021-5069 and SynDWell-US do not supply a comparable Alaska or Hawaii row.
• The USGS depth study was limited to available digital records. The authors state that a comprehensive quality-assurance inspection of every source was outside the study's scope.
• USGWD is a static compilation with source-specific dates. Its state data were collected between August 2021 and January 2024. Later agency records are not included unless a newer source is separately cited.
• State databases are not censuses of active wells. Pre-reporting wells, unsubmitted reports, undigitized paper records, restricted records, and records with unusable locations can be missing. The absence is not random.
• Activity status is incomplete. USGWD reports 58.5 percent of records as active, 9.9 percent inactive, and 31.6 percent unknown.
• Potential duplicates remain in USGWD. The study flagged 1,421,235 potential duplicate records but retained them when the evidence did not establish that they represented the same physical well.
• Location-quality counts are not inventory totals. The California, Wisconsin, Michigan, Texas, Rhode Island, Connecticut, West Virginia, and New Hampshire values in Table 2 are records retained for the USGWD geospatial analysis, not current counts of all wells in those states.
• The state-source index covers 13 states. It is Edition 1 of the downloadable provenance dataset. The omitted states are not assigned inferred agencies, dates, or counts.
• A state or county value cannot predict a parcel. Even a well-constructed median describes a record population. It is not a site investigation, drilling specification, yield estimate, water-quality result, or budget for a new well.

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What files are included with the provenance dataset?

The production package includes the original 13-state provenance dataset as CSV and JSON, plus a data dictionary and change log. The files reproduce Table 1, distinguish agency totals from USGWD geospatial QA counts, retain nulls rather than guesses, and carry a July 23, 2026 verification date.

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What primary sources support this page?

The list prioritizes original producers: federal reports and data releases, state agencies, official statutes and regulations, and the original peer-reviewed national database paper.

1. Degnan, J.R., Kauffman, L.J., Erickson, M.L., Belitz, K., and Stackelberg, P.E., 2021, Depth of groundwater used for drinking-water supplies in the United States: U.S. Geological Survey Scientific Investigations Report 2021-5069. https://doi.org/10.3133/sir20215069
2. U.S. Geological Survey, Data for depth of groundwater used for drinking-water supplies in the United States (ver. 2.0, January 2026). https://doi.org/10.5066/P94640EM
3. McCarthy, P.M., Larsen, J.D., Ransom, R.K., Dieter, C.A., and Niswonger, R., 2026, Synthesized Domestic Well Database for the Conterminous United States (SynDWell-US). https://doi.org/10.5066/P13JP4JQ
4. U.S. Geological Survey, Minnesota Geological Survey, and Minnesota Department of Health, 2022, National Water-Well Database: State Water-Well Records for Minnesota. https://doi.org/10.5066/P9ME4BO7
5. U.S. Geological Survey and Michigan Department of Environment, Great Lakes, and Energy, 2025, National Water-Well Database: State Water-Well Records for Michigan. https://doi.org/10.5066/P1DBMHQ9
6. U.S. Geological Survey and Louisiana data partners, 2026, National Water-Well Database: State Water-Well Records for Louisiana. https://doi.org/10.5066/P137JNNH
7. Lin, C.-Y., Miller, A., Waqar, M., and Marston, L.T., 2024, A database of groundwater wells in the United States: Scientific Data, volume 11, article 335. https://doi.org/10.1038/s41597-024-03186-3
8. Lin, C.-Y., Miller, A., Waqar, M., and Marston, L.T., 2024, A Database of Groundwater Wells in the United States, HydroShare data release. https://doi.org/10.4211/hs.8b02895f02c14dd1a749bcc5584a5c55
9. Dieter, C.A., Maupin, M.A., Caldwell, R.R., Harris, M.A., Ivahnenko, T.I., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2018, Estimated use of water in the United States in 2015: U.S. Geological Survey Circular 1441. https://doi.org/10.3133/cir1441
10. U.S. Geological Survey, Domestic (Private) Supply Wells. usgs.gov/mission-areas/water-resources/science/domestic-private-supply-wells
11. California Department of Water Resources, Well Completion Reports. water.ca.gov/programs/groundwater-management/wells/well-completion-reports
12. California Department of Water Resources, Well Completion Reports Feature Service, including known data issues. gis.water.ca.gov/arcgis/rest/services/Environment/i07_WellCompletionReports/FeatureServer
13. California Legislative Information, Water Code §13751. leginfo.legislature.ca.gov
14. Minnesota Geological Survey, County Well Index. cse.umn.edu/mgs/cwi
15. Minnesota Department of Health, Minnesota Well Index. health.state.mn.us/communities/environment/water/mwi
16. Texas Water Development Board, Groundwater Data. twdb.texas.gov/groundwater/data
17. Texas Water Development Board, Submitted Drillers Reports Database Reports and Downloads. twdb.texas.gov/groundwater/data/drillersdb.asp
18. Pennsylvania Department of Conservation and Natural Resources, Pennsylvania Groundwater Information System. pa.gov/agencies/dcnr/conservation/water/groundwater
19. Pennsylvania DCNR, Submit Groundwater and Water Well Data. pa.gov/services/dcnr/submit-groundwater-and-water-well-data
20. Florida Department of Environmental Protection, Water Well Contractor Licensing and Permitting. floridadep.gov/water/source-drinking-water/content/water-well-contractor-licensing-and-permitting
21. South Florida Water Management District, Form 62-532.900(2), State of Florida Well Completion Report. sfwmd.gov
22. Florida DEP, Water Management Districts. floridadep.gov/owper/water-policy/content/water-management-districts
23. Michigan EGLE, Wellogic. michigan.gov/egle/maps-data/wellogic
24. Michigan EGLE, Water well construction statistics in Michigan. michigan.gov/egle
25. Wisconsin DNR, Look up groundwater and well data. dnr.wisconsin.gov/topic/Groundwater/Data.html
26. Wisconsin DNR, Well and heat exchange notification. dnr.wisconsin.gov/topic/Wells/constructionNotification.html
27. Louisiana DENR, For Water Well Owners. dnr.louisiana.gov/wellowners
28. Ohio DNR, Ohio Water Well Database. waterwells.ohiodnr.gov
29. New Hampshire Geological Survey, Water Well Inventory feature service. gis.des.nh.gov
30. Connecticut DCP, Well Drilling Completion Reporting. portal.ct.gov/dcp
31. Connecticut eRegulations, R.C.S.A. §25-128-62, Completion reports. eregulations.ct.gov
32. Connecticut General Assembly, Conn. Gen. Stat. §25-131, Well records. cga.ct.gov/current/pub/chap_482.htm
33. Rhode Island DOH, Private Well Care, Repairs, and Construction. health.ri.gov/private-wells
34. Spechler, R.M., and Kroening, S.E., 2007, Hydrology of Polk County, Florida: U.S. Geological Survey Scientific Investigations Report 2006-5320. https://doi.org/10.3133/sir20065320
35. U.S. Geological Survey, Ground Water Atlas of the United States, Chapter G: Intermediate aquifer system. pubs.usgs.gov/ha/ha730/ch_g/G-text5.html
36. U.S. Geological Survey, Floridan aquifer system. usgs.gov/mission-areas/water-resources/science/floridan-aquifer-system
37. Lindsey, B.D., Belitz, K., Cravotta, C.A. III, Toccalino, P.L., and Dubrovsky, N.M., 2021, Lithium in groundwater used for drinking-water supply in the United States. pubs.usgs.gov/publication/70218019
38. U.S. Geological Survey, Lithium in groundwater used for drinking-water supply in the United States. usgs.gov/publications/lithium-groundwater-used-drinking-water-supply-united-states

Last verified: July 23, 2026 · Byline: Lakeland Well Pump Repair Research

Lakeland Well Pump Repair Research is the independent research and reference section of lakelandwellpumprepair.com.

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