By the Closer Look Inspectors team · Facts checked October 2026 against Iowa DNR, Iowa HHS, State Hygienic Laboratory and EPA sources · About our inspectors
A VOC result reports fuel and industrial chemicals, such as benzene and trichloroethylene, that can be found in drinking water. Iowa DNR says to test for volatile organic chemicals when a well is near fuel tanks or a commercial or industrial area.
All the water tests we offer
Bacteria
Shows whether surface water or waste is reaching the well.
- Surface contamination reaching the well
- Fecal contamination from septic, manure or wildlife
Health chemicals
No taste, color or smell. These are the long-term health checks.
- Fertilizer, septic and manure; highest risk to infants10 mg/L (EPA)
- Natural arsenic from rock and soil10 µg/L (EPA)
- Lead service lines, solder and brass fixtures
- ManganeseNatural manganese; a concern for infants
- FluorideNatural fluoride; dental health4.0 mg/L (EPA)
- UraniumNatural radionuclide in groundwater30 µg/L (EPA)
Petroleum & solvents
Fuel and chemical spills from old tanks or nearby sites.
Household quality
Staining, scale and taste, and choosing the right treatment.
- IronRusty staining and metallic taste
- HardnessScale buildup; sizing a water softenerNo health standard
- pHCorrosive or scaling water6.5 to 8.5, aesthetic (EPA)
- SulfateTaste and odor; diarrhea risk for infants250 mg/L, aesthetic (EPA)
Limits shown are EPA drinking water standards. Compare your lab results with these values.
Health standard: EPA and Iowa DNR (567 IAC 41.5): 0.005 milligrams per liter (mg/L), or 5 micrograms per liter (µg/L), for benzene and trichloroethylene in public water; DNR (567 IAC 135.9): 5 µg/L for benzene in drinking water wells within 1,000 feet of a petroleum release.
Where VOCs come from in Iowa
EPA ties benzene to leaching from gas storage tanks and landfills. It ties trichloroethylene to metal degreasing sites and other factories, and tetrachloroethylene to factories and dry cleaners. In Iowa, the underground tank rules name benzene, ethylbenzene, toluene and xylenes as chemicals of concern from petroleum. Groundwater samples from a petroleum release covered by those rules must always be analyzed for them. One Iowa example is Climbing Hill, a town of about 120 residents on private wells. Gasoline and diesel fuel leaking from two underground tanks contaminated several of those wells. The contamination was first found in 1990.
Health effects and who is most at risk
EPA lists the potential long-term effects of benzene above its limit as anemia, a decrease in blood platelets and an increased risk of cancer. For trichloroethylene it lists liver problems and an increased risk of cancer. Benzene is a volatile organic chemical. A 2004 Iowa health review of the Climbing Hill wells noted that its vapors can be inhaled while bathing or showering in contaminated water. EPA says small children, elderly adults, and anyone who is pregnant or nursing are often more vulnerable to pollutants. Iowa DNR's levels for drinking water wells near a petroleum release are, in micrograms per liter: benzene 5, toluene 1,000, ethylbenzene 700 and xylenes 10,000. The Iowa review added that a result above EPA's limit does not mean health problems will result. It does mean action to reduce levels is necessary.
Signs and when to test
Iowa DNR says to test for volatile organic chemicals if a well is near fuel tanks or a commercial or industrial area. Iowa's underground tank rules apply the levels they set for drinking water wells to any drinking water well within 1,000 feet of a release source. EPA's chart adds a gas station, dry-cleaning operation, factory, dump, junkyard or landfill nearby. It also lists an odor of gasoline or fuel oil near a gas station or buried fuel tanks. EPA says to test a private well right away if the odor, color or taste of the water changes. Iowa DNR notes that water that looks clear and tastes great may still be unsafe to drink. DNR also says a shallow well, or one finished in shallow bedrock, is more vulnerable to contamination than a deeper, protected well. A home purchase is a sensible time to get a baseline result.
If your result is high: what to do next
EPA says to have the well re-tested to confirm the result. In Climbing Hill, residents with affected wells were given bottled water shortly after contamination was found. Point-of-use treatment systems with carbon filters, which treat water before it reaches the tap, were later installed. Filtered tap water showed a marked reduction in contaminants, and the review warned that the filters must be maintained properly and changed regularly. DNR then installed new community wells. EPA adds that, depending on the contaminant, its concentration and the condition of the well, you may need a new source of water or a new well. Under Iowa's underground tank rules, DNR can require a tank owner to find out whether the tank is the source. That applies when regulated substances turn up in nearby drinking waters and another party brings it to DNR's attention.
Facts checked October 2026 against: iowadnr.gov, epa.gov, epa.gov, legis.iowa.gov, legis.iowa.gov, atsdr.cdc.gov.
Iowa private well testing timeline
| Test | Year 1 | Year 2 | Year 3 | Year 4 | Year 5 | Year 6 |
|---|---|---|---|---|---|---|
| Coliform bacteria | ||||||
| Nitrate | ||||||
| Arsenic |
When to test your water
- Every yearColiform bacteria and nitrate, the basic safety checks for a private well.
- At least onceArsenic and manganese. Iowa DNR's testing list repeats arsenic every 3 years.
- Before a baby drinks the waterNitrate. Water above 10 mg/L as nitrogen should not be used for infant formula or juice.
- When you buy a homeA full baseline while you can still ask questions or negotiate.
- New well or well workWhen a well is new and after service on the well or pump.
- After a flood or power outageIf flood water was near or reached the well, or an outage dropped the water pressure.
- When taste, color or smell changesA change in the water is a reason to test.
- Near a fuel tankVOCs, plus DRO for diesel and fuel oil. Iowa DNR names gasoline among the VOCs some wells are susceptible to, and Iowa's well rules list 100 feet between a well and a liquid fuel storage tank other than propane.
- City water in an older homeLead. Iowa DNR says homes built before 1986 are more likely to have lead pipes, fixtures and solder.
Based on: Iowa DNR private wells, Iowa DNR testing frequency, Iowa DNR why test, Iowa DNR floods, State Hygienic Laboratory, 567 IAC 49.
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How far a well must be from common hazards in Iowa
- Property line4 ft
- Building sewer line10 ft
- LP gas tank15 ft
- Roadside ditch15 ft
- Stream, pond, lake or wetland25 ft
- Septic tank50 ft
- Septic absorption field100 ft
- Fuel oil or gasoline tank100 ft
- Fertilizer or chemical storage150 ft
Septic, feedlot or fuel tank near the well? A coliform and nitrate test shows whether it is reaching the water. Get a free instant quote
Buying a home with a well in Iowa: what happens at the sale
- Groundwater Hazard StatementIowa Code 558.69 requires a groundwater hazard statement filed with the declaration of value when a listed condition (including any known well and its status under 455B.190, or a private sewage disposal system) exists on the property, signed by a seller or agent, with a copy given to the buyer.
- Wells on the propertyIf known wells are on the property, the statement must give the approximate location of each and its status under Iowa Code 455B.190 (abandoned wells properly plugged); the owner is responsible for the accuracy of the information.
- Septic time-of-transfer inspectionIowa Code 455B.172(11) requires a private sewage disposal system serving a building to be inspected before any transfer of ownership, by a DNR-certified inspector, and the county recorder will not record the deed without the report or a binding acknowledgment.
- Failing systemsA system that is failing to treat wastewater must be renovated to current standards by the seller or, by agreement and within a reasonable time set by the county board of health or DNR, by the buyer (455B.172(11)(c)).
The paperwork tells you a well exists, not what is in it. Add water testing to your inspection. Get a free instant quote
Quick answers
What are VOCs in well water?
VOCs are volatile organic compounds, a group of chemicals tied to fuel and industrial sources. Benzene is one. EPA links benzene to gas storage tanks, trichloroethylene to metal degreasing sites, and tetrachloroethylene to dry cleaners. Each chemical has its own limit. Iowa DNR uses 5 µg/L for benzene and 1,000 µg/L for toluene in drinking water wells near a petroleum release.
Should I test my well for VOCs if there is a gas station nearby?
A nearby gas station is a listed reason. EPA's chart pairs a gas station or dry-cleaning operation nearby with testing for volatile organic compounds. Iowa DNR says the same for a well near fuel tanks or a commercial or industrial area. Iowa's underground tank rules apply the levels they set for drinking water wells to any drinking water well within 1,000 feet of a release source.
Can you smell or taste VOCs in drinking water?
Not reliably. Iowa DNR says water that looks clear and tastes great may still be unsafe to drink. It adds that unless you test regularly, you will not know if the water is safe to use. EPA says to test right away when the odor, color or taste changes. It also lists an odor of gasoline or fuel oil near a gas station or buried fuel tanks as a reason to test for VOCs.
How do you remove VOCs from well water?
It depends on what is found. In Climbing Hill, Iowa, point-of-use carbon filters on affected private wells cut contaminant levels at the tap, but the filters must be maintained properly and changed regularly. EPA says that, depending on the contaminant, its concentration and the condition of the well, you may need a new source of water or a new well.
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