Private well owners in Central Florida are responsible for their own water quality. Unlike municipal customers who receive annual water quality reports, private well owners receive no automatic notification when contaminants appear. The Florida Department of Health recommends testing for total coliform bacteria at least once a year and after any event that could affect well integrity (https://www.floridahealth.gov/environmental-health/drinking-water/private-well-water.html). Beyond bacteria, Central Florida well owners should test for nitrate, arsenic, and in some locations PFAS. This guide explains what to test for, when to test, how to read your results, and which treatment options address each contaminant.
Why Private Well Owners in Florida Bear Sole Responsibility for Their Water Quality
Florida has more than 700,000 private wells serving roughly 1.7 million residents, according to the Florida Department of Health well program data at https://www.floridahealth.gov/environmental-health/drinking-water/private-well-water.html. The Safe Drinking Water Act and its state counterpart (Florida Safe Drinking Water Act) regulate public water systems, not private wells. That means no government agency monitors the quality of water coming out of your tap, and no agency will notify you if your groundwater becomes contaminated.
The Floridan Aquifer, which supplies most private wells in Central Florida, is a generally high-quality water source. But it is not immune to contamination. Agricultural runoff, septic system leachate, industrial discharge, naturally occurring minerals, and surface water intrusion through damaged well casings all create pathways for contaminants to reach private wells. The only way to know what is in your water is to test it.
Testing is also required by Florida law in certain situations. Florida Administrative Code Rule 62-532 requires water quality testing when a new well is constructed, when an existing well is repaired or deepened, and when a well is permitted for certain uses. For routine annual testing, no state mandate applies to private wells, but the Florida DOH and EPA both strongly recommend it.
What Contaminants to Test for in a Central Florida Private Well
A baseline annual water test for a Central Florida private well should cover the contaminants most likely to be present given the Floridan Aquifer geology and the land uses common in Central Florida counties. The following covers each one and why it matters.
Total Coliform Bacteria
Total coliform is the primary indicator test for bacterial contamination in drinking water. The coliform group includes dozens of bacterial species that are naturally present in soil and water. When coliforms appear in a well, they indicate that surface water or soil water is finding a pathway into the well, which could also allow pathogens to enter.
The EPA Maximum Contaminant Level for total coliform in public water systems is zero detectable colony-forming units (CFU) per 100 mL under the Revised Total Coliform Rule (https://www.epa.gov/dwreginfo/revised-total-coliform-rule-and-total-coliform-rule). The same standard is used as the action level for private wells by the Florida DOH. A positive total coliform result triggers a requirement to retest and investigate the source of contamination.
E. coli (Fecal Coliform)
E. coli is the most important single indicator in a well water test. Unlike the broader total coliform group, E. coli is a specific indicator of fecal contamination from human or animal waste. Sources include failing septic systems, surface drainage from pastures or feedlots, and wildlife. In heavily agricultural Central Florida counties such as Marion, Polk, and Osceola, E. coli in private wells is a documented concern.
Any detectable E. coli in drinking water is considered unsafe. The EPA MCL is zero. A positive E. coli result requires immediate action: stop using the water for drinking and cooking, disinfect the well, and identify the contamination source before resuming use. Do not rely on boiling alone if the contamination pathway remains open.
Nitrate
Nitrate is the most common chemical contaminant in private wells nationally, according to USGS groundwater quality assessments (https://www.usgs.gov/special-topics/water-science-school/science/nitrate-and-drinking-water). In Central Florida, the primary sources are nitrogen-based fertilizers (both agricultural and residential), septic system effluent, and animal waste. Nitrate is colorless, odorless, and tasteless and cannot be detected without a test.
The EPA MCL for nitrate is 10 mg/L (10 parts per million) as nitrogen. High nitrate is most dangerous for infants under six months old because it interferes with the blood's ability to carry oxygen, causing a condition called methemoglobinemia (blue baby syndrome). For adults, the primary concern is long-term exposure at elevated levels; emerging research suggests associations with certain health effects at concentrations above the MCL. Verify current EPA guidance at https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations.
Treatment for nitrate at the point of use is reverse osmosis or ion exchange (nitrate-specific resin). Standard carbon filters and water softeners do not reliably remove nitrate. Whole-house treatment for nitrate is possible with ion exchange but is more expensive than point-of-use RO. For households with infants or pregnant women, a point-of-use RO at the kitchen sink is the most practical protective measure.
Arsenic
Arsenic occurs naturally in the limestone and clay formations through which the Floridan Aquifer passes. In some Central Florida counties, particularly in areas where the surficial aquifer overlies older geological formations, naturally occurring arsenic above the EPA MCL has been documented in private wells. A USGS national study of arsenic in drinking water found elevated arsenic in wells across Florida, with higher concentrations in certain geological settings (https://pubs.usgs.gov/pp/1803/downloads/pp1803.pdf).
The EPA MCL for arsenic is 10 micrograms per liter (10 parts per billion). Long-term exposure above the MCL is associated with increased risk of skin, bladder, and lung cancers, cardiovascular disease, and diabetes. Arsenic has no taste or odor; testing is the only way to detect it.
Treatment options for arsenic include point-of-use reverse osmosis (the most effective for residential use, removing 90 to 99 percent) and whole-house adsorptive media systems using iron-based or titanium dioxide-based media. The correct choice depends on your arsenic concentration, water volume, and co-occurring contaminants. High iron in the water requires pre-treatment before an arsenic adsorption system will work effectively. See our iron and sulfur treatment guide for Central Florida iron concentrations and treatment options.
PFAS (Per- and Polyfluoroalkyl Substances)
PFAS are synthetic chemicals that have contaminated groundwater in areas near military bases, airports, and industrial sites that used AFFF firefighting foam. Central Florida has several military installations and airports with documented or potential AFFF use histories. A 2023 USGS study estimated that approximately 45 percent of U.S. private wells sampled had detectable PFAS at some level (https://www.usgs.gov/news/national-news-release/usgs-study-finds-pfas-in-nearly-half-us-tap-water).
Standard well water tests do not include PFAS. You must specifically request a PFAS panel using EPA Method 533 or EPA Method 537.1 from a certified laboratory. The EPA April 2024 rule set a 4 parts-per-trillion limit for PFOA and PFOS in public water systems; private well owners are advised to use the same threshold. For a full treatment and testing guide for PFAS, see our PFAS in private wells guide.
Other Parameters Worth Testing
Beyond the primary health-based contaminants, a complete Central Florida well water test should also include:
- pH: Floridan Aquifer water is typically alkaline (pH 7.5 to 8.5), but some wells, particularly in surficial aquifer zones, can be corrosively acidic. Low pH corrodes copper plumbing and fixtures and leaches lead from solder.
- Hardness: Central Florida water is among the hardest in the United States due to calcium and magnesium from the limestone aquifer. Hardness causes scale buildup, shortens appliance life, and increases soap consumption. Testing establishes the baseline for sizing a water softener. See our water softener guide for sizing logic.
- Iron: Iron above 0.3 mg/L (the EPA Secondary MCL) causes staining on fixtures, laundry, and irrigation systems and feeds iron bacteria. Iron concentration determines which treatment technology is appropriate. See our iron treatment guide for concentration-to-treatment mapping.
- Hydrogen sulfide: The rotten-egg odor common in Florida well water. A field test or lab test confirms presence. Hydrogen sulfide is corrosive to copper plumbing and unpleasant at any detectable level.
- Manganese: Often co-occurs with iron in Central Florida wells. Manganese at high concentrations causes black staining and has been associated with neurological effects at long-term elevated exposure. The EPA secondary MCL is 0.05 mg/L.
When to Test Your Well: A Florida-Specific Schedule
The Florida Department of Health recommends the following testing schedule for private well owners (https://www.floridahealth.gov/environmental-health/drinking-water/private-well-water.html):
| When to Test | What to Test For |
|---|---|
| Annually (minimum) | Total coliform bacteria, nitrate, pH |
| When buying a home with a well | Full panel: bacteria, nitrate, arsenic, hardness, iron, pH, turbidity, PFAS if near risk area |
| After flooding or heavy rain intrusion | Total coliform, E. coli, turbidity |
| After pump replacement or well repair | Total coliform, E. coli (after disinfection) |
| If taste, odor, or appearance changes | Full panel, plus hydrogen sulfide and iron if applicable |
| After nearby land use change (new agricultural operation, construction) | Nitrate, bacteria, turbidity, PFAS if applicable |
| Hurricane Well Decontamination (post-hurricane) | Coliform, turbidity, nitrate; follow our hurricane decontamination guide |
How to Read Your Well Water Lab Report
Lab reports vary by laboratory, but they share a common structure. Understanding the key fields helps you act correctly on the results.
Units: Bacteria results are typically reported as CFU/100 mL (colony-forming units per 100 milliliters) or as presence/absence (P/A). Chemical results are in mg/L (milligrams per liter, equivalent to parts per million) or ug/L (micrograms per liter, equivalent to parts per billion). PFAS results are in ng/L or ppt (nanograms per liter, equivalent to parts per trillion).
MCL (Maximum Contaminant Level): The federal or state regulatory limit for public water systems. For private well decision-making, treat the MCL as the action threshold: results above the MCL warrant treatment.
Detection Limit (DL or MDL): The lowest concentration the method can reliably detect. A result reported as "less than DL" or "ND" (not detected) means the contaminant was below that threshold, not necessarily absent. For health-based decisions, confirm the lab's detection limit is below the MCL so you know the test would catch a problem if one exists.
What to do with results above the MCL:
- Total coliform positive: Confirm with a repeat test. If confirmed, shock-chlorinate the well following Florida DOH guidelines (https://www.floridahealth.gov/environmental-health/drinking-water/private-well-water.html) and retest. Use only bottled water for drinking and cooking until the well tests clear.
- E. coli positive: Stop use immediately. Disinfect. Identify and seal the contamination pathway before resuming use. A well contractor should inspect the casing and wellhead seal.
- Nitrate above 10 mg/L: Install a point-of-use RO for drinking and cooking water, especially if infants or pregnant individuals are in the household. Investigate the source (fertilizer application timing, septic proximity) to determine whether the concentration is seasonal or persistent.
- Arsenic above 10 ug/L: Install a point-of-use RO or adsorptive media system. Confirm that the treatment system is sized and verified for your arsenic concentration and your water chemistry.
How to Collect a Well Water Sample Correctly
Improper sample collection is the most common cause of incorrect well water test results. Contamination of the sample container or failure to purge standing water in the plumbing produces results that do not reflect actual well water quality. Follow these steps:
- Use a certified lab sample kit. The lab provides sterilized bottles appropriate for each test type. Bacteria bottles contain sodium thiosulfate to neutralize chlorine. PFAS bottles are made from PFAS-free plastics. Do not use your own containers.
- For bacteria samples, do not purge first. Collect the first water from the tap to capture any bacteria residing in the line. Remove aerators or screens from the tap before sampling because bacteria can accumulate there and produce a false positive. Wipe the faucet with an alcohol swab and allow it to dry before opening the bacteria sample bottle.
- For chemical parameters (nitrate, arsenic, metals), purge first.Run the cold water tap for two to five minutes to flush the standing water in the plumbing and draw water directly from the aquifer. Collect the sample without touching the inside of the bottle or cap.
- Keep samples cold during transport. Bacteria samples in particular must be refrigerated and reach the lab within the holding time specified by the lab (typically six hours for coliform samples). Ship with ice packs for overnight delivery if you cannot deliver directly.
- Complete the chain-of-custody form. The form documents collection time, sample location, and the name of the person who collected it. Certified labs require this documentation for results to be legally defensible.
We can assist you with arranging certified lab testing for your Central Florida well. For properties with pump systems we service, we often include water sampling at the annual service visit. Call us at (352) 771-2325 or schedule a consultation to discuss your testing needs.
Treatment Options for Bacteria and Other Contaminants
The right treatment depends on what your test results show. This section maps common Central Florida well water problems to their solutions.
Bacteria and Coliform Treatment
The two primary approaches for treating bacterial contamination in private wells are shock chlorination and continuous disinfection.
Shock chlorination is a one-time disinfection procedure that kills bacteria in the well casing, pump, and distribution lines. It uses household bleach (sodium hypochlorite) introduced into the well at concentrations that create a residual chlorine level throughout the system, followed by a holding period, flushing, and retesting. The Florida DOH publishes a detailed shock chlorination procedure at https://www.floridahealth.gov/environmental-health/drinking-water/private-well-water.html. Shock chlorination is appropriate when coliform contamination follows a specific event (flood, pump repair, storm intrusion). It is not a permanent solution if the contamination pathway is still open.
Continuous UV disinfection is the preferred ongoing treatment for wells that test positive for bacteria repeatedly or for wells at high risk of contamination due to location (near pastures, near septic systems, in flood-prone areas). A UV system installed after sediment and iron pre-treatment provides continuous disinfection without chemical addition. UV does not change the taste, odor, or chemistry of the water, and it leaves no disinfection byproducts. Annual lamp replacement maintains performance. For wells with recurring coliform, UV disinfection combined with a casing inspection to seal the contamination pathway is the durable solution.
Nitrate Treatment
Point-of-use reverse osmosis at the kitchen sink is the most practical nitrate treatment for residential wells. A properly maintained RO membrane removes 90 to 95 percent of nitrate from the treated permeate (verify current treatment effectiveness data at https://www.epa.gov/ground-water-and-drinking-water/types-drinking-water-treatment). Ion exchange using anion resin (nitrate-selective) is the whole-house alternative for households where nitrate treatment at every tap is required.
Standard water softeners use cation exchange resin and do not remove nitrate. Activated carbon filters and sediment filters do not remove nitrate. Boiling water concentrates nitrate rather than reducing it.
Arsenic Treatment
Point-of-use RO is again the most practical solution for most households with arsenic-affected wells. For whole-house arsenic treatment, adsorptive media systems using ferric hydroxide-based granular media or titanium dioxide media have documented effectiveness for arsenic removal in the mg/L concentration range. Media must be periodically tested and replaced; saturated media will pass arsenic through. Whole-house arsenic systems require pre-treatment to remove iron and turbidity that would foul the media and shorten its service life.
Building a Complete Treatment System for a Contaminated Well
When a Central Florida well tests positive for multiple contaminants, which is common, treatment decisions interact. The sequencing and sizing of systems matter. A common scenario: the well tests high in hardness, iron, and coliform, with nitrate just under the MCL.
A well-engineered system for that scenario would typically sequence as:
- Sediment pre-filter to protect all downstream equipment from sand and particulates common in Floridan Aquifer wells.
- Iron and hydrogen sulfide treatment (air injection system or catalytic carbon) before the water softener. Iron above 0.3 mg/L fouls softener resin and will also foul UV sleeves and RO pre-filters faster. See the iron treatment guide for the full Central Florida treatment matrix.
- Water softener to remove hardness before it can scale UV sleeves, foul downstream filters, or damage appliances. See the water softener guide for sizing by Central Florida hardness levels.
- UV disinfection system to continuously inactivate any bacteria reaching the household distribution system. Positioned after softening so iron and turbidity are low enough for effective UV penetration.
- Point-of-use RO at the kitchen sink to remove nitrate, arsenic (if present), PFAS (if present), and any residual organics or minerals at the drinking and cooking tap.
Every system we design starts from your actual lab results. We do not sell systems to address contaminants that are not in your water. If you are in our service area covering Orange, Osceola, Lake, Polk, Marion, Alachua, Seminole, Volusia, and surrounding Central Florida counties, we can review your test results with you and recommend a system sized for your specific water chemistry and household water use. Call (352) 771-2325 or schedule a free consultation.
How Florida Law and EPA Rules Apply to Your Private Well
Florida regulates private wells under Chapter 373, Florida Statutes (Water Resources), and the rules in Florida Administrative Code Chapter 62-532 (Water Well Construction). These rules cover:
- Well construction standards: casing depth, grouting, wellhead protection zones, and required setback distances from septic systems and property lines. Florida requires a minimum 75-foot horizontal setback between a well and a septic system drainfield, and 50 feet from a septic tank. Verify current setback rules at https://www.floridahealth.gov/environmental-health/onsite-sewage/index.html.
- Contractor licensing: all well construction, repair, and abandonment in Florida must be performed by a licensed water well contractor. Quality Filters And Pumps holds Florida Water Well Contractor License #7494 (verify at https://www.myfloridalicense.com).
- Water quality testing requirements at new construction and certain change-of-use situations.
For well owners who discover contamination above MCLs, the USDA Rural Development program offers WaterSense loans and grants for water system improvements for eligible rural homeowners (https://www.rd.usda.gov/programs-services/water-environmental-programs/water-waste-disposal-loan-grant-program). The Florida DOH Environmental Health office in each county can provide referrals to programs that assist low-income well owners with remediation costs.
Related Well Water Guides from Quality Filters And Pumps
Bacteria and coliform are one part of the well water quality picture. The guides below cover the other contaminants and systems most relevant to Central Florida private well owners:
- Well Water Filtration: A Complete Treatment Guide covers hardness, iron, hydrogen sulfide, sediment, low pH, and treatment sequencing for the Floridan Aquifer.
- PFAS in Private Wells: What Central Florida Well Owners Need to Know covers PFAS testing, the 2024 EPA rule, and treatment options.
- Iron and Sulfur Well Water Treatment Near Ocala explains why Central Florida wells have high iron and sulfide and which treatment technology fits each concentration level.
- Well Pump Troubleshooting Guide covers the five most common pump failure patterns and how to diagnose them.
- Water Softener Installation in Central Florida covers sizing, placement, and what to expect from installation on Floridan Aquifer water.
- Residential RO System Repair in Central Florida covers membrane replacement, pre-filter service, and troubleshooting for reverse osmosis systems on well water.
- Hurricane Well Decontamination for Central Florida Wells covers the steps for safely returning a well to service after flooding or storm damage.
- Well Drilling in Central Florida explains aquifer geology, permits, casing, and what depth affects water quality and chemistry.