Well Water Testing in Colorado: What to Test For, Labs & Costs
Updated October 2026 · Every price, limit and lab below was checked against its primary source this month (sources)
About 7% of Coloradans drink from a private well (USGS, as cited by CDPHE), and nobody tests those wells but the owner: CDPHE says private wells aren't covered by the federal Safe Drinking Water Act, so testing is up to you apart from a few local rules and lender requirements. This guide covers what a Colorado well should be tested for and how often, which contaminants turn up where in the state, where to get the water tested (including free programs), what labs charge, and what to do with the results.
Every year
Bacteria + nitrateTotal coliform/E. coli, nitrate/nitrite, TDS and pH (CDPHE's annual list).
Every 3–5 years
Metals + uraniumArsenic, uranium, fluoride, manganese, iron, lead, copper, hardness.
Foothills & mountains
Add radiationUranium, gross alpha and radon in water: 38–40% of uranium samples in Jefferson and Boulder counties hit the limit.
What it costs
$20–$42 / $200+A bacteria test at a public lab; a full homeowner package at a private lab.
Free options
PFAS statewideFree PFAS tests for private wells statewide (CDPHE) and free bacteria + nitrate kits in Jefferson County, while supplies last.
Heads up
State lab: bacteria onlyCDPHE's lab has suspended water chemistry testing. Use a certified lab for nitrate, arsenic, uranium.
Current status, October 2026: the state lab (CDPHE's Colorado Public Health Laboratory in Denver) has temporarily suspended water chemistry testing while it works with EPA on quality-control issues; samples it received after December 27, 2024 were not processed, and CDPHE gives no reopening date. It still tests for bacteria (total coliform and E. coli, $20 on the fee sheet it links, which is dated July 2025–June 2026, so confirm the current price). For nitrate, arsenic, uranium and other chemistry, use one of the labs below.
What to Test Your Well For, by Situation
The first three rows are CDPHE's schedule. The rest are our recommendations for specific situations, built on the agency guidance named in each row; where a test is our suggestion rather than an agency's, the row says so. Start with the row that fits you, then check the contaminant table for anything specific to your part of Colorado.
| Your situation | Test for | Why / source |
|---|---|---|
| Routine, every year | Total coliform bacteria (with E. coli), nitrate/nitrite, total dissolved solids (TDS), pH | CDPHE's annual list. These are indicators: they show whether germs or chemicals may be getting in. |
| Every 3–5 years | Arsenic, copper, fluoride, hardness, iron, lead, manganese, uranium | What CDPHE calls the common Colorado contaminants. EPA separately says to test for radionuclides every three years. |
| New well, or no test history | A broad baseline: alkalinity, arsenic, barium, calcium, chloride, chromium, copper, fluoride, iron, lead, magnesium, nitrate/nitrite, pH, selenium, sodium, sulfate, sulfur, PFAS, total coliform, TDS, uranium and a VOC (volatile organic compound) screen | CDPHE's new-well list. Keep the report: it is the baseline every later test is compared to. |
| Buying a home | At minimum bacteria and nitrate; in the foothills add uranium and gross alpha; anything your lender requires | We found no statewide test-at-sale rule; lenders set their own requirements, and one Jefferson County area requires a test at title transfer. See buying a home. |
| Pregnancy, or a baby in the house | Nitrate/nitrite and bacteria now; we also suggest manganese, arsenic, uranium and lead if you have no recent results | CDPHE says to test when someone becomes pregnant or a child moves in. Nitrate above the limit can seriously sicken infants under six months (EPA), and EPA advises a lower manganese limit for infants. |
| After a flood | Bacteria, after the well has been disinfected; more if chemicals may have reached it | EPA: don't turn the pump on until an electrician or well contractor has checked it, and don't drink or wash with the water; have the well disinfected, then test for bacteria 7–10 days later. Disinfection does nothing for fuel, pesticides or metals. |
| After a wildfire | Bacteria at minimum; VOCs and SVOCs if fire damage nearby was heavy or the well has plastic (PVC, HDPE) or rubber parts; consider lead, copper, zinc and iron | CDC guidance for wells after a wildfire: don't drink the water until it has been tested. |
| Near cropland, feedlots or a septic field | Nitrate every year (not just once), bacteria; ask the lab about a pesticide screen | Fertilizer, manure and septic systems are nitrate sources (EPA). In CDPHE's county data, Weld and Morgan stand out (table). |
| Near oil and gas development | A VOC screen (it covers benzene and related compounds) plus your routine tests; keep the results | Colorado's oil and gas rules (ECMC Rule 615) have operators sample nearby water sources, with the owner's consent, before and after drilling; your own baseline is still worth having. |
| Near old mines | A general metals panel (CDPHE suggests the 23 Target Analyte List metals by EPA method 200.8) | CDPHE's advice for historic mining areas. The Colorado Geological Survey maps historic mines. |
| Taste, smell or color changed; unexplained stomach illness; a neighbor's well has a problem; after repairs or a spill | Bacteria and nitrate at least, plus whatever the neighbor found or the spill involved | All on CDPHE's list of reasons to test now rather than on schedule. |
Not sure? CDPHE's toxicology line, ToxCall (303-692-2606), answers questions about what to test for and what results mean.
Colorado Well Contaminants: Where They Occur, Limits, What to Do
Where tested wells went over the limit
CDPHE's private well lab results, 2011–2020: the share of tests in each county that came back at or over the health limit. Highest counties first.
Uranium
Counties with at least 20 tests; 47 counties had fewer.
Nitrate
Counties with at least 20 tests; 30 counties had fewer.
Arsenic
Counties with at least 20 tests; 31 counties had fewer.
Bacteria
Counties with at least 20 tests; 35 counties had fewer.
Where-in-Colorado figures come mostly from CDPHE's private well dataset (lab results from 2011–2020, by county, for arsenic, nitrate, uranium and coliform), plus Colorado Geological Survey and USGS studies. People test when they have a reason to, so these are signals of where problems show up, not the odds for your well. Limits are EPA's standards for public water systems. They don't legally apply to a private well, but they are the benchmark CDPHE and labs use.
| Contaminant | Where in Colorado | Health limit | If you're over it |
|---|---|---|---|
| Coliform bacteria / E. coli | Statewide. Total coliform was positive in 125 of 508 samples (25%) in Jefferson County, 67 of 241 (28%) in Boulder County and 23 of 85 (27%) in Montrose County. | Should be absent | Coliform alone points to a pathway into the well; E. coli means fecal contamination. Drink another source, disinfect (shock chlorinate) the well, check the cap and casing, retest. Details |
| Nitrate / nitrite | Farm counties stand out in CDPHE's data: 287 of 1,741 samples (16.5%) over the limit in Weld County, 14 of 45 in Morgan County; also 17 of 126 in Park County. | Nitrate 10 mg/L as N; nitrite 1 mg/L as N | Don't give it to infants, including in formula. Don't boil it (boiling concentrates nitrate). Reverse osmosis, distillation or ion exchange treat it (CSU Extension). |
| Uranium | Front Range: 77 of 203 samples (38%) in Jefferson County and 53 of 134 (40%) in Boulder County at or above the limit, maximums 2,100 and 2,700 µg/L; Adams County 18 of 70 (26%). CGS also found exceedances concentrated in Fremont County and in shallow alluvial wells along the lower Arkansas River. | 30 µg/L | Kidney toxicity and cancer risk over years of drinking. Boiling doesn't help. EPA names reverse osmosis and ion exchange point-of-use systems. |
| Gross alpha / radium | Not in CDPHE's dataset. CGS sampling of 91 private wells in the lower Arkansas Valley: 57 (63%) over the gross alpha standard and 29 over the radium standard, radium mostly in deeper Dakota Sandstone wells. | Gross alpha 15 pCi/L; radium-226+228 5 pCi/L | A high gross alpha result is usually followed up with a radium test. Same treatment family as uranium (reverse osmosis, ion exchange). |
| Radon in water | Granite and Denver Basin wells. USGS found radon above EPA's proposed 300 pCi/L level widespread in Dawson and Arapahoe aquifer wells. | No federal limit (EPA proposed 300 pCi/L, or 4,000 pCi/L with an air program, in 1999) | Test your home's air first; CDPHE says that if the air test shows a radon problem and you're on a private well, test the water too. See our radon guide. |
| Arsenic | Western Colorado and the San Luis Valley: 44 of 182 samples (24%) over the limit in Montrose County (max 1,420 µg/L), 10 of 59 in Ouray County. A 2026 USGS-listed study found arsenic at or above 5 µg/L in 19.8% of the San Luis Valley private wells it measured. | 10 µg/L | Long-term cancer and circulatory risk. Retest to confirm, then treat: point-of-use reverse osmosis or an arsenic adsorption cartridge for most homes; ask the lab whether you have arsenic III, which needs oxidizing first (New Hampshire DES guidance). |
| Fluoride | Not in CDPHE's dataset. In USGS sampling of Denver Basin bedrock wells, roughly 10–24% of samples from the Denver, Arapahoe and Laramie-Fox Hills aquifers were above 2 mg/L; none from the Dawson. | 4.0 mg/L; 2.0 mg/L secondary | Above 2 mg/L children's teeth can discolor; above 4 mg/L, bone effects (EPA). Pick a treatment unit certified for fluoride; ask ToxCall about a result between 2 and 4. |
| Manganese | Not tracked county by county; CDPHE lists it among common Colorado contaminants to test every 3–5 years. | Health advisory 0.3 mg/L (lifetime); 0.05 mg/L secondary (staining) | Not just cosmetic: EPA's advisory says infants under six months shouldn't drink water above 0.3 mg/L even short-term; its 10-day advisory level for everyone else is 1 mg/L. Treat with a unit certified for manganese. |
| Iron | Not tracked county by county; on CDPHE's 3–5-year list of common Colorado contaminants. | No health limit; 0.3 mg/L secondary | Rusty color, metallic taste, orange staining (EPA). A treatment choice, not a health emergency. |
| Hardness, TDS, sulfate | Varies well to well; TDS is on CDPHE's annual list as an indicator. | No health limit; TDS 500 mg/L and sulfate 250 mg/L secondary | Scale, deposits, salty taste. TDS is one of CDPHE's annual indicators, so a big change from your last result is worth asking the lab or ToxCall about. |
| Lead and copper | Usually from plumbing and well parts rather than the aquifer (EPA lists household plumbing corrosion as the main source). | Lead: action level 15 µg/L (10 µg/L from Nov. 2027); copper 1.3 mg/L | Lead harms children's development; EPA's health goal for lead is zero. Find and replace the source, or use a unit certified for lead. |
| PFAS | CDPHE piloted free PFAS testing in Park County (Bailey) in 2024 and now offers it statewide. | PFOA and PFOS 4.0 ng/L (parts per trillion) each | CDPHE's PFAS TAP gives a free filter dispenser, while supplies last, to households with results above an EPA standard. See free testing. |
| VOCs (benzene and others) | Spills, fuel tanks, oil and gas activity, and wildfire-damaged plastic well parts. | Benzene 5 µg/L; others vary | Stop drinking the water, call ToxCall and your local public health agency, and retest with a certified lab. |
To compare your own numbers against these limits, CDPHE has an interactive tool, Understanding your well water test results; enter your lab values in the units shown.
How Often to Test Well Water in Colorado
- Every year: bacteria (total coliform, E. coli), nitrate/nitrite, TDS and pH. CDPHE says more often if pregnant or breastfeeding people, small children or older adults drink the water.
- Every 3–5 years: arsenic, copper, fluoride, hardness, iron, lead, manganese and uranium (CDPHE). EPA says every three years for radionuclides, so foothills owners should use the three-year end.
- Every 3–6 months while a nitrate result is high or borderline (CSU Extension).
- Right away after any of the triggers in the situation table: a flood or fire, repairs, a spill, a change in the water, a new baby.
Free and Low-Cost Well Water Testing in Colorado
- Free PFAS testing: CDPHE PFAS TAP (statewide) Anyone with a private well in Colorado can apply; people on a public water system aren't eligible. A contractor mails a sampling kit with a prepaid return label, and results arrive about two weeks after testing. If a result is above an EPA standard, the household can get a free filter dispenser (pitcher or countertop size). Offered while supplies last. Questions: 303-906-8052.
- Free bacteria and nitrate kits: Jefferson County Jefferson County Public Health offers free bacteria and nitrate test kits to private well owners in the county while supplies last. Fill out the county's Private Well Water Testing Application first, then pick the kit up from Environmental Health Services, 100 Jefferson County Parkway, Golden (303-232-6301).
- Free VOC testing: Weld County Weld County residents whose drinking water comes from a private well can have it screened for volatile organic compounds (VOCs), the chemicals of concern near oil and gas activity, free twice a year. The county lab collects the sample itself. Sign the county's notice of public disclosure form, then call the lab at (970) 400-2278. Outside Weld County the same test is $167.
- Gilpin County Public Health: $30 bacteria + nitrate/nitrite $30 covers total coliform, E. coli, nitrate and nitrite ($2 extra by card). The county notes its nitrate/nitrite result only shows presence, so a positive needs a follow-up quantitative test from a nitrate-certified lab. Samples Monday–Wednesday, 8 a.m.–4 p.m., within 24 hours of collection; 15193 Hwy 119, Black Hawk.
- CDPHE state lab: $20 bacteria test Total coliform and E. coli presence/absence. Bottles ship free by FedEx (not to P.O. boxes); the sample must reach the lab within 24 hours of collection; most results come back within 72 hours. Details in the state lab section.
Near oil and gas: Colorado's rules (ECMC Rule 615) require operators of new oil and gas wells to sample up to four available water sources within a half mile, with the owner's consent, before drilling and at set intervals afterward, and to send the owner the lab results.
Where to Get Well Water Tested Near You
The short version: for a bacteria test, use your county lab if it has one (table below) or the state lab. For chemistry and radiation, use a lab certified by CDPHE for that specific test. Certification is per test method, so a lab can be certified for bacteria and nothing else.
- Find certified labs: CDPHE's accredited drinking water lab lookup filters by test and city. It doesn't recommend specific labs.
- Check they take homeowners: CDPHE keeps a separate list of labs it has confirmed will test private well water (not exhaustive, not an endorsement). Some big labs don't take homeowner samples at all.
- Call before you collect: confirm the test, the method, the price, the bottles and the holding time. Your local public health agency can tell you what it offers.
Nearest options by area
| Area | Nearest options |
|---|---|
| Evergreen, Conifer, Bailey, Indian Hills (local page) | GeoWater Services (Evergreen); free Jefferson County bacteria + nitrate kits; Gilpin County lab; PFAS TAP |
| Colorado Springs, Black Forest, Falcon, Woodland Park, Divide | El Paso County Public Health lab (bottle pickup in Divide and other sites) |
| Denver metro, Boulder, Greeley, Douglas County | State lab (bacteria); Weld County lab (Greeley; bacteria, chemistry and well packages); for chemistry, Hazen (Golden), SGS (Wheat Ridge) or GeoWater's packages. Call each to confirm homeowner testing and price. |
| Fort Collins, Loveland, Estes Park and Larimer County | Larimer County Environmental Health takes well water samples on Tuesdays at its Fort Collins (1525 Blue Spruce Dr.) and Loveland (200 Peridot Ave.) offices, in its own approved bottles; Estes Park has bottles but no drop-off. For chemistry, Technology Laboratory (Fort Collins) or the Weld County lab. (970) 498-6775. |
| Grand Junction, Glenwood Springs, Western Slope | Mesa County Regional Lab (bacteria); a certified lab by mail for chemistry |
| Durango and the Four Corners | La Plata County Water Quality Lab (bacteria) |
| San Luis Valley | SDC Laboratory, Alamosa (packages include arsenic) |
| Steamboat and Routt County | Routt County Environmental Health; CSU Extension Routt office for broader tests |
| Weld County and the northeast plains | Weld County Public Health lab; Northeast Colorado Health Department, Sterling |
| Park County | PFAS TAP; GeoWater (Evergreen); a certified lab by mail |
CDPHE state lab (bacteria only, for now)
Order bottles with CDPHE's private customer bottle order form; they ship free by FedEx, not to P.O. boxes, and the lab won't accept samples in bottles it didn't provide. Fill out the chain of custody form that comes with them. Pay at drop-off, or enclose a check if you ship. Drop-off is at 8100 E. Lowry Blvd., Denver (receiving door on the south side), weekdays only; check CDPHE's page for current hours. Shipped samples must go overnight and arrive within 24 hours of collection.
County and public health labs
| Lab | Tests and published price | Practical details |
|---|---|---|
| El Paso County Public Health, Colorado Springs | Bacteria $23; nitrate $30; nitrite $30; fluoride $30; pH $22; real estate package (bacteria, nitrate, nitrite) $80 | Lab at 1675 W. Garden of the Gods Rd. Bottles mailed for a $10 shipping fee, or picked up at county sites. 719-578-3199. |
| Mesa County Regional Lab, Grand Junction | Coliform with E. coli $30 (2026 price) | Request a kit online. Drop-off Monday–Thursday, 8 a.m.–4 p.m.; 510 29½ Road. |
| La Plata County Water Quality Lab, Durango | Private well bacteria $30 | Kits and drop-off at 211 Rock Point Dr., Monday–Thursday, 8 a.m.–3:30 p.m.; no samples on Fridays. Refers other tests to certified labs. |
| Routt County Environmental Health, Steamboat Springs | Bacteria kit $30 | 136 6th St., Suite 201. For broader tests the county points to CSU Extension's Routt office. |
| Gilpin County Public Health, Black Hawk | Bacteria + nitrate/nitrite $30 | See above. |
| Northeast Colorado Health Department, Sterling | Bacteria; will also collect samples for other tests, including nitrate. No published price. | NCHD supplies sterile bottles; samples taken at the Sterling office on Tuesdays. |
| Weld County Public Health lab, Greeley | Bacteria $25; nitrate $23; arsenic, uranium, lead or other single metals $23 each; Annual Package (bacteria, nitrate, nitrite, pH, TDS) $109; Private Drinking Water Well package $245, or $314 with arsenic, copper and lead; Heavy Metals Screen (including arsenic and uranium) $207; VOCs free for Weld residents (2026 prices). CDPHE lists it as certified for bacteria, nitrate, fluoride, and metals including arsenic and uranium. | Runs its tests in house. Prices and the full test list are on its 2026 chain-of-custody form; payment is due at drop-off. Bacteria samples accepted Monday–Thursday until 4 p.m., not the day before a holiday. (970) 400-2278. |
CDPHE also lists Boulder, Delta, El Paso, Fremont, Larimer, Las Animas, Mesa and Pueblo county health departments as places where a courier can pick up a sample for the state lab. Call the county first: the sample still has to reach the lab within 24 hours, and CDPHE's courier information page cautions against relying on the courier for bacteria samples for that reason. Driving or overnight shipping is safer.
Colorado labs on CDPHE's private well testing list
"Certified for" comes from CDPHE's drinking water certification list (checked October 2026). Phone numbers are as CDPHE lists them.
| Lab | Location | CDPHE certified for |
|---|---|---|
| GeoWater Services | Evergreen, (720) 861-0944 | Coliform bacteria only (see packages below) |
| Hazen Research | Golden, (303) 279-4501 | Gross alpha/beta, radium-226/228, uranium, arsenic and other metals, nitrate, fluoride |
| Sangre de Cristo Laboratory (SDC) | Alamosa, (719) 589-1024 | Bacteria, nitrate, fluoride, arsenic, lead, copper, cadmium (its posted 2026–27 chemistry certificate is provisional) |
| SGS North America | Wheat Ridge, (303) 425-6021 | Metals including arsenic and uranium, nitrate, fluoride, VOCs, pesticides |
| Eurofins Reservoirs Environmental | Arvada, (303) 736-0100 | Coliform bacteria |
| Technology Laboratory | Fort Collins, (970) 490-1414 | Nitrate, fluoride, VOCs |
| EAnalytics Laboratory | Loveland, (970) 667-6975 | Coliform bacteria |
| M.M.S. Environmental Laboratories | Fort Collins, (970) 286-2930 | Coliform bacteria |
| Colorado State University | Fort Collins, (970) 491-5061 | Total coliform |
| IEH-Warren Analytical Laboratory | Greeley, (970) 475-0252 | Coliform bacteria |
| Murray-Brown Laboratories | Northglenn, (303) 296-0264 | Coliform bacteria (its site lists a $250 work-order minimum) |
| Northeast Colorado Health Department | Fort Morgan / Sterling, (970) 867-4918 | Coliform bacteria |
| Culligan Analytical Laboratory; EMSL Analytical | Englewood; Denver | Certifications are held by out-of-state locations of these labs |
| Green Analytical Laboratories | Durango, (970) 247-4220 | Listed, but its certification showed as expired; ask before using |
| Colorado Analytical Laboratory | Commerce City | Metals including uranium, nitrate, fluoride, VOCs, PFAS; but its own site now asks homeowners to use GeoWater Services instead |
CDPHE's list also includes out-of-state labs that accept mailed samples, such as Energy Laboratories (Casper, Wyoming), National Testing Laboratories (Ohio) and Pace Analytical. Don't send homeowner samples to Colorado Analytical Laboratory: it now refers homeowners to GeoWater.
Labs with published homeowner well packages
- GeoWater Services, Evergreen Published residential packages: Basic Water Quality $200 (bacteria, nitrate, fluoride, copper, iron, manganese, hardness, pH, TDS and more; 3–5 business days); Mountain Well Quality $525 (adds gross alpha, gross beta, uranium, radon and lead; 4–6 weeks); Radiochemistry $350 (gross alpha, gross beta, uranium, radon, lead; 4–6 weeks); Heavy Metals $475 (arsenic, lead, barium, cadmium, chromium, mercury, selenium, silver); VA Package $175 (bacteria, lead, nitrate, nitrite). The packages don't include radium. Its CDPHE certification covers coliform bacteria, so if a lender or permit needs certified chemistry or radiochemistry results, ask which lab runs those tests. 303-670-3348.
- SDC Laboratory (Sangre de Cristo Laboratory), Alamosa Its private well chain-of-custody form (September 2026) lists a Private Well Package for $240 (bacteria, alkalinity and hardness, chloride, fluoride, nitrate, nitrite, phosphate, sodium, sulfate, TDS, pH, arsenic, cadmium, copper, iron, lead and manganese), a Loan Package for $120 (bacteria, nitrate, nitrite, lead) and Bacteria Only for $42; prices "subject to change." No uranium or radon. 2329 Lava Lane; 719-589-1024.
- Weld County Public Health lab, Greeley Its 2026 chain-of-custody form lists a Private Drinking Water Well package for $245 (bacteria, alkalinity, pH, fluoride, nitrate, nitrite, chloride, sulfate, TDS, hardness, sodium, plus a free VOC screen), the same with arsenic, copper and lead for $314, an Annual Package for $109 (bacteria, nitrate, nitrite, pH, TDS), a HUD/Real Estate Package for $94 (bacteria, nitrate, nitrite, lead) and a Heavy Metals Screen for $207 (antimony, arsenic, barium, copper, cadmium, mercury, lead, selenium, uranium). It takes samples from outside Weld County too. (970) 400-2278.
- Hazen Research, Golden One of the Colorado labs CDPHE lists as certified for drinking-water radiochemistry (gross alpha/beta, radium-226/228) and accepting outside samples; also certified for uranium and arsenic, and on CDPHE's private well list. An industrial lab that prices tests individually rather than as well packages, so call before collecting.
How Much Well Water Testing Costs in Colorado
Published prices from each lab's own fee page, checked October 2026. Turnaround is the lab's own figure.
| Test | Price | Where | Turnaround |
|---|---|---|---|
| Bacteria (total coliform + E. coli) | $20–$42 | CDPHE state lab $20; El Paso $23; Weld $25; Mesa, La Plata, Routt $30; SDC $42 | State lab: most within 72 hours |
| Bacteria + nitrate/nitrite | Free–$80 | Jefferson County kits free; Gilpin $30 (presence only); El Paso real estate package $80; Weld HUD/real estate package (adds lead) $94 | Ask the lab |
| Nitrate alone | $23–$30 | Weld County $23; El Paso County $30 | Ask the lab |
| Basic well package | $200–$314 | GeoWater Basic $200; SDC Private Well Package $240 (includes arsenic); Weld Private Drinking Water Well $245, or $314 with arsenic, copper and lead | GeoWater: 3–5 business days |
| Radiochemistry (uranium, gross alpha, radon) | $350–$525 | GeoWater Radiochemistry $350, or Mountain Well package $525 with the basics included | 4–6 weeks |
| Heavy metals | $207–$475 | Weld County Heavy Metals Screen $207 (includes uranium); GeoWater $475 | GeoWater: 2 weeks |
| PFAS | Free | CDPHE PFAS TAP | About 2 weeks after testing |
| VOCs (oil and gas chemicals) | Free–$167 | Weld County lab: free for Weld residents, $167 otherwise | Ask the lab |
So a foothills well owner starting from nothing should budget roughly $200 for a basic package plus $350 for radiochemistry (or $525 combined at GeoWater), plus the free PFAS test; a plains well owner can cover the annual basics for $30–$80 at a county lab, adding a package with arsenic every few years. Prices change; confirm before you collect.
How to Take a Well Water Sample
Always use the lab's own bottles and follow its instructions; these steps follow CDPHE's instructions for its bacteria bottle.
- Wear nitrile or latex gloves. Keep pets and running fans out of the room.
- Pick a cold-water tap that doesn't leak, doesn't swivel and has no aerator. Kitchen faucets usually swivel and have aerators; a bathtub spigot is often best.
- Run the cold water for 3–5 minutes, then turn it off.
- Wipe the inside and outside of the spigot with rubbing alcohol (not bleach, which reacts with the bottle's preservative) and let it dry.
- Turn the cold water back on to a slow, steady stream. Remove the cap without touching its inside or setting it down. Don't rinse the bottle.
- Fill to the lab's line (the state lab rejects bacteria bottles under 100 mL or over 120 mL), cap tightly, and refrigerate or pack with ice packs.
- Label the bottle with your name, the tap, and the date and time, matching the lab's form.
- Get it to the lab fast: the state lab and most county labs require delivery within 24 hours. The state lab takes samples weekdays only, so don't ship before a weekend or holiday.
Package tests can differ, and radon and VOC samples need their own bottles and handling. When the kit's instructions differ from these, follow the kit.
Reading Your Results, and What to Do Next
CDPHE's advice for any result above a drinking water standard: consider drinking an alternate source until you can treat the water, contact your local public health agency, and talk to your health care provider. Boiling kills germs but does not remove chemicals, and it concentrates nitrate. Beyond that:
Positive Coliform or E. coli
Total coliform without E. coli means a path for contamination into the well or plumbing; E. coli means fecal contamination, so use bottled water for drinking and cooking. Disinfect (shock chlorinate) the well (CDPHE links a shock chlorination video; EPA says drilled wells are best disinfected by a well or pump contractor), then retest. CSU Extension advises retesting after about a week; EPA's flood guidance says 7–10 days after disinfection. If it comes back positive again, look for the way in: CDPHE's checklist is a cracked or damaged casing, a broken or missing cap, a settled or cracked surface seal, and a casing less than 12 inches above ground.
High Nitrate or nitrite
Over 10 mg/L nitrate as nitrogen (some labs report nitrate as NO3, where the equivalent is 45 mg/L) or 1 mg/L nitrite: no infants, including in formula. CSU Extension adds pregnant women and adults with reduced stomach acid to the at-risk list, lists reverse osmosis, distillation and ion exchange as treatments (not carbon filters or softeners), and recommends retesting every three to six months while results are high or borderline. Look for the source too: septic fields, manure and fertilizer near the well.
High Uranium, gross alpha, radium or arsenic
These are long-term risks, not emergencies, but stop drinking the water until it's treated. Retest to confirm before buying equipment. For radionuclides EPA names point-of-use reverse osmosis and ion exchange systems (spent media can need special disposal; ask the installer). For arsenic, New Hampshire's environment agency recommends point-of-use treatment (reverse osmosis or an adsorption cartridge) at the drinking tap for most homes, with whole-house treatment for very high levels or when children or others may drink from untreated taps, and testing which form of arsenic you have, because arsenic III needs oxidizing first. A result many times over the limit is worth a call to ToxCall the same day.
Check Manganese, fluoride, lead
Manganese over 0.3 mg/L matters for infants under six months (EPA). Fluoride between 2 and 4 mg/L is a tooth-discoloration issue for children; over 4 mg/L is a health limit. EPA lists household plumbing corrosion as the usual source of lead. Choose a treatment unit certified for the specific contaminant.
Nuisance Iron, hardness, TDS, sulfate
Mostly taste, staining and scale at typical levels (EPA's secondary standards). Worth treating for comfort, not urgent for health.
Choosing treatment: no single system removes everything. CDPHE recommends checking any treatment product against the NSF certified product listings or the Water Quality Association's certified product search for the contaminant you need removed, and replacing filters, membranes or UV lamps as the manufacturer says (usually yearly). Then test the treated water. Local treatment companies are on our resources page.
Help reading a report: CDPHE's well water results tool; CSU's water quality interpretation tool; ToxCall (303-692-2606, CDPHE); and the national Wellcare Hotline (888-395-1033).
Buying a Home With a Well
We found no statewide Colorado rule requiring a well test when a house sells (one Jefferson County area is the exception, below). For a mortgage, the lender decides what testing is needed (El Paso County's lab notes this directly), so ask the lender before you order anything. Test anyway: bacteria and nitrate are the minimum, and in the foothills add uranium and gross alpha. Allow for lab time; radiochemistry can take 4–6 weeks, which may not fit a short inspection window.
A water test is not a well inspection. The water test tells you what's in the water today. A well or pump contractor can check the things that decide what it will be tomorrow: the casing, cap and seal, the pump and pressure system, and how much water the well actually produces, which in fractured foothills rock can be very little (see our geology page). The well's permit, construction and pump records are available from the Colorado Division of Water Resources.
Jefferson County: the county's well testing rules run through septic permits. In the Indian Hills/Parmalee Gulch area, a coliform bacteria and nitrate result is required before the county issues a septic construction, repair or Use (transfer of title) permit, so homes there are tested when they sell. A well test is also a condition of septic permits on parcels created before June 3, 1966. Otherwise Jefferson County Public Health says there are no regulatory requirements to test your well; the county's water supply page adds that testing is required when a well is drilled or the pump is changed.
Priority Tests by Area
Beyond the annual basics, based on the data in the contaminant table:
| Area | Add these tests | Why |
|---|---|---|
| Jefferson and Boulder county foothills (Evergreen, Conifer, Indian Hills, Nederland) | Uranium, gross alpha; radon in water if your home's air test is high | 38–40% of uranium samples at or above the limit |
| Bailey and Park County | Nitrate, PFAS; a metals panel near old mines; radon in water if your air test is high | 17 of 126 nitrate samples over the limit; PFAS pilot area |
| Denver Basin wells (Douglas, Elbert, El Paso, Black Forest) | Radon in water, fluoride (deeper aquifers) | USGS Denver Basin sampling |
| Fremont County and the lower Arkansas Valley | Uranium, gross alpha, radium, selenium (radium needs a radiochemistry-certified lab) | Colorado Geological Survey well sampling |
| San Luis Valley | Arsenic (essential), uranium | 19.8% of measured wells at or above 5 µg/L arsenic |
| Weld, Morgan and the northeast plains | Nitrate every year; a VOC screen near oil and gas | 16.5% (Weld) and 31% (Morgan) of nitrate samples over the limit |
| Montrose and Ouray counties (Western Slope) | Arsenic | 24% of Montrose arsenic samples over the limit |
More local detail is on our community pages, including the Front Range cities of Golden, Arvada, Littleton, Castle Rock, Brighton, Erie, Broomfield and Denver.
Sources (checked October 2026)
- CDPHE: Water testing services (chemistry suspension, sampling instructions, courier drop-off sites) and its linked fee sheet (July 1, 2025–June 30, 2026)
- CDPHE: Drinking water: private wells; Drinking water lab certification (certified lab lookup)
- CDPHE: PFAS Testing and Assistance Program; Testing your home for radon
- Colorado Environmental Public Health Tracking (CDPHE): Private well water and your health (testing schedule, situations, confirmed-lab list, inspection checklist, treatment advice), private well water data, 2011–2020, Understanding your well water test results
- Colorado Geological Survey: private well baseline studies, Wet Mountains (OF-22-10) and Lower Arkansas River (OF-25-06)
- USGS: Denver Basin bedrock aquifer water quality (SIR 2014-5051); Smith et al. 2026, San Luis Valley groundwater arsenic (Environ. Sci. & Technol.)
- EPA: National Primary Drinking Water Regulations; Secondary drinking water standards; Natural radionuclides in private wells; What to do with your private well after a flood; Drinking Water Health Advisory for Manganese (2004)
- CDC: Private wells after a wildfire
- CSU Extension: Nitrates in drinking water; bacteria in water guidance
- New Hampshire Department of Environmental Services: Arsenic in New Hampshire Well Water (WD-DWGB-3-2)
- ECMC: Rule 615, Groundwater Baseline Sampling and Monitoring (600 Series rules)
- Colorado Division of Water Resources: Well permitting and records
- Jefferson County: Well water systems; Form 100 OWTS application (well testing policies)
- Fee and service pages of El Paso County Public Health, Mesa County Regional Lab, La Plata County, Routt County, Gilpin County, Northeast Colorado Health Department, Larimer County Environmental Health (drinking water sampling, November 2026), Weld County Public Health lab (2026 chain-of-custody form, November 2026), GeoWater Services, SDC Laboratory and Hazen Research; Colorado Analytical Laboratory customer page; CDPHE courier information page