Texas county well guide

Well Water in Collin County, TX: Testing, Contractors and Rules

About 9,810 households in Collin County, 3% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
3%of households on a private well
Share on wells, county vs state
Collin County3%
Texas average5%
47licensed contractors serve the county
6 mito the nearest certified lab, SPL, Inc. – Plano
Nostatewide test required when a home is sold

Wells are the exception in Collin County: about 9,810 households, under 3% of the county, are on a private well. Being in the minority means less local help, so this page gathers what applies.

Local rules for wells in Collin County

The rules that apply in Collin County are set at the state level in Texas. The state does not require a test on a new well, and nothing is required at sale. Some counties and townships add permits or setbacks of their own, so check locally before drilling. The state's own recommendations are below.

At a glance

Water test for a new wellNot required statewide

No statewide test. The driller must hold a TDLR license, build the well to the 16 TAC Chapter 76 standards (setbacks from septic systems and property lines, cement seal, disinfection) and file a State of Texas Well Report within 60 days. Nobody samples the water unless you do. If your county has a groundwater conservation district, it may require the well to be registered or permitted before drilling; domestic wells on larger tracts are usually exempt from permitting but not from registration.

Water test when a home is soldNot required statewide

No statewide requirement. The seller's disclosure notice only says whether the water comes from a well. FHA, VA and USDA loans normally require a bacteria, nitrate and lead sample from an accredited lab before closing, and a few groundwater districts ask for a well inspection when a tract changes hands.

What the state recommends

Texas A&M AgriLife Extension and TCEQ recommend a coliform bacteria test every year and a nitrate test every year, plus a first-time panel of arsenic, fluoride, total dissolved solids, hardness, iron, manganese, sulfate and pH. Add uranium and gross alpha in the Hill Country and the Panhandle, and PFAS near airfields and military bases. Test again after flooding, repairs or any change in taste, color or smell.

Free or low-cost testingAvailable

The Texas Well Owner Network (Texas A&M AgriLife Extension) runs low-cost screening days around the state, usually $10 to $15 a sample for bacteria, nitrate, arsenic and salinity, with results explained at a follow-up meeting. County and city health department labs listed below sell bacteria tests at cost. The DSHS laboratory in Austin also sells mail-in kits.

Getting your water tested near Collin County

The nearest certified lab is SPL, Inc. – Plano in Plano, about 6 miles from the county center. There are 2 more within 40 miles, listed below with what each tests for.

3 certified labs within 40 miles

Licensed well contractors serving Collin County

Licensed help in Collin County includes 4-M Drilling and AAA Water Well Service and 45 others. Every listing was matched to the Texas license list; the "verify" link on each profile opens the state lookup.

Well depth and water chemistry

Well depth and water chemistry in Collin County follow the rock underneath it. Typical wells here run 100 to 400 ft in the Ogallala on the High Plains; 200 to 800 ft in the Trinity and Edwards limestones of the Hill Country and North Texas; 100 to 600 ft in the Gulf Coast and Carrizo-Wilcox sands of East and South Texas; shallower along river alluvium. Contaminants worth testing for in this part of Texas include nitrate (high plains, rolling plains, central texas farm country), arsenic (southern high plains.

Typical well depth

Varies by location. Check the state well record search for logs of nearby wells.

Contaminants to test for
  • Nitrate (High Plains
  • Rolling Plains
  • Central Texas farm country)
  • Arsenic (southern High Plains
  • Gulf Coast
  • Trans-Pecos)
  • Fluoride (West Texas and the Panhandle)
  • Radium and uranium (Hickory aquifer around the Llano Uplift
  • Parts of the Ogallala)
  • High total dissolved solids and salinity (West and South Texas)
  • Coliform bacteria
  • Hardness (Edwards and Trinity limestones)
  • Iron and manganese and hydrogen sulfide (East Texas)
  • PFAS near military airfields

Neighboring counties: Denton County, Rockwall County, Dallas County, Hunt County.

What well work costs in Collin County

Bacteria test (coliform and E. coli)$20published Texas lab fees
Nitrate test$15published Texas lab fees
Broad panel (metals and minerals)$85 to $450state and university lab packages
Well inspection$250 to $550$350 to $900 with water testing
Submersible pump replacement$1,000 to $2,500installed; deep wells cost more
Pressure tank replacement$800 to $1,500installed
One treatment unit$700 to $3,500softener, iron filter or UV, installed
Multi-stage whole-house treatment$2,500 to $10,000+several units or whole-house RO, installed
New well, complete$6,000 to $16,000typical 200 ft well with pump; drilling alone about $20 to $30 per foot; deeper wells cost more
Shock chlorination$80 to $200by a contractor; under $30 to do yourself

City utility labs charge $20 for bacteria (Wichita Falls, Midland); Texas A&M AgriLife screenings cover bacteria, nitrate and salinity for $15 (a screening, not a certified test). Installed costs are national 2026 ranges; local quotes vary with depth, access and materials. Sources, checked September 2026: City of Wichita Falls, Texas A&M AgriLife well screening, HomeGuide cost guides, Angi: cost to shock a well.

Questions Collin County well owners ask

How many homes in Collin County are on a well?

About 9,810, or 3% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Collin County?

SPL, Inc. – Plano in Plano, about 6 miles away. Call first to ask whether they accept homeowner samples.

Do I need a permit to drill a well in Collin County?

No statewide test. The driller must hold a TDLR license, build the well to the 16 TAC Chapter 76 standards (setbacks from septic systems and property lines, cement seal, disinfection) and file a State of Texas Well Report within 60 days. Nobody samples the water unless you do. If your county has a groundwater conservation district, it may require the well to be registered or permitted before drilling; domestic wells on larger tracts are usually exempt from permitting but not from registration.

What does a well test cost near Collin County?

Published lab fees in Texas: $20 for a bacteria test and $15 for nitrate. City utility labs charge $20 for bacteria (Wichita Falls, Midland); Texas A&M AgriLife screenings cover bacteria, nitrate and salinity for $15 (a screening, not a certified test). Mail-in kits cost about the same as walking in.