Typical values from 66 sampled wells in Seminole County · Full groundwater profile
What Are You Noticing in Your Water?
Pre-selected from Seminole County well data. Untick anything you do not notice in your own water.
Based on the contaminants most commonly reported in this region. Always confirm with a certified lab water test before buying equipment.
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Nearly all homes in Seminole County, in Central Florida, are on public water. The Florida Department of Health's 2022 inventory counts 4.7% of built parcels, roughly 7,398 properties, on private wells, mostly on rural lots outside utility service areas.
Most groundwater pumped in Seminole County comes from the Floridan Aquifer (USGS, 2015 withdrawals). Samples from 65 local wells put the median hardness at 8.9 gpg (hard) and median iron at 0.11 mg/L. The county's largest communities are Sanford, Altamonte Springs and Oviedo.
In this guide
Groundwater Profile: Seminole County
Most groundwater pumped in Seminole County comes from the Floridan Aquifer (USGS, 2015 withdrawals). Across 65 sampled wells, the median hardness is 8.9 gpg, which the USGS classes as hard. It applies to wells across Seminole County, including around Sanford, Altamonte Springs and Oviedo.
What shows up in local well samples:
- HardnessMedian 8.9 gpg; 68% of 65 sampled wells above 7 gpg
Calcium and magnesium dissolved from limestone. Leaves scale on fixtures and water heaters and reduces soap lather. Not a health risk.
Water softener sizing
Hydrogen sulfide (the rotten-egg smell) was measured in only 0 Seminole County wells, too few to say how common it is. Limited local data (fewer than 20 samples): individual well testing recommended. If you notice the smell, a sulfide test confirms it.
How Seminole County Compares to Florida and the U.S.
See How Seminole County Compares to Florida & the US
| Share of wells with… | Seminole CountySeminole | FloridaFL | United StatesUS |
|---|---|---|---|
| Hard water (above 7 gpg) | 68% | 79% | 60% |
| Iron above 0.3 mg/L | 38% | 35% | 19% |
| Manganese above 0.05 mg/L | 0% | 8% | 21% |
| Dissolved solids above 500 mg/L | 22% | 22% | 15% |
| Acidic water (pH below 6.5) | 22% | 15% | 14% |
| Nitrate above 10 mg/L (EPA limit) | No data | 2% | 4% |
| Arsenic above 10 µg/L (EPA limit) | 2% | 3% | 7% |
| Median hardness | 8.9 gpg | 12.4 gpg | — |
| Median pH | 7.4 | 7.2 | 7.3 |
Seminole County and Florida: share of sampled wells (all well types, samples since 2000) whose typical value exceeds the level, from the Water Quality Portal. United States: USGS Circular 1332, about 2,100 domestic wells in 48 states sampled 1991 to 2004. Well types and years differ, so read this as a broad comparison. Highlighted cells are well above the national share.
See what a typical Seminole County well needs
Opens the diagnostic calculator with Seminole County median values (8.9 gpg hardness, 0.11 ppm iron, pH 7.4) for a 3–4 person home. Swap in your own lab results for an exact plan.
Testing Your Well in Seminole County
The Florida Department of Health in Seminole County oversees private well permitting in the county and investigates suspected contamination. For routine bacteria, nitrate or full-panel tests, use a laboratory certified by the Florida Department of Health.
What to test for in Seminole County:
- Bacteria (total coliform and E. coli) and nitrate, at least once a year (Florida Department of Health recommendation)
- Hardness in grains per gallon (gpg) to size a softener
- After any flood, new well work or a change in taste, color or smell
The Florida Department of Health in Seminole County can explain how to collect samples and where to send them. Statewide guidance is on the FDOH private well testing page, and our guide to how to test well water covers which tests to order.
Nearby Counties
Seminole County borders these counties with published reports:
Frequently Asked Questions
How many homes in Seminole County use private wells?
The Florida Department of Health’s Florida Water Management Inventory (2022 data) found 4.7% of built parcels in Seminole County on private wells, roughly 7,398 properties.
How hard is well water in Seminole County?
Groundwater samples from 65 wells in Seminole County have a median hardness of 8.9 grains per gallon (153 mg/L), which the USGS classes as hard. About 68% of sampled wells are above 7 gpg, the point where a water softener is usually worthwhile. The Florida statewide median is 12.4 gpg.
Is iron a problem in Seminole County well water?
The median iron level across 66 sampled wells is 0.11 mg/L, below the EPA aesthetic guideline of 0.3 mg/L, and 38% of wells exceed it. Most wells will not stain, but if yours does, a lab test tells you whether iron or manganese is the cause.
Why does my well water smell like rotten eggs in Seminole County?
Hydrogen sulfide (the rotten-egg smell) was measured in only 0 Seminole County wells, too few to say how common it is. Limited local data (fewer than 20 samples): individual well testing recommended. If you notice the smell, a sulfide test confirms it. The smell is a nuisance rather than a health risk at typical levels.
Which aquifer supplies wells in Seminole County?
Most groundwater pumped in Seminole County comes from the Floridan Aquifer (USGS, 2015 withdrawals).
Does boiling well water make it safe to drink in Seminole County?
Only if bacteria are the problem. A one-minute rolling boil kills germs, but it does not remove nitrate, arsenic or other chemicals, and it concentrates them as water evaporates. Test first, and see our boiling well water myth buster for when boiling helps.
How often should I test my well water in Seminole County?
The Florida Department of Health recommends testing private wells for bacteria and nitrate at least once a year, and again after flooding or well repairs. The Florida Department of Health in Seminole County can explain how to collect and submit samples.
Written by Well Water Advisor Editorial Team.