Private wells are common in Horry County (USGS), and on a well you are the one responsible for what comes out of the tap. Here is what the local groundwater is like, what goes wrong most often, and what to test.
How many Horry County homes are on wells?
The most recent county-level government figure is a USGS estimate for 2015. That year, 103,189 of Horry County’s 309,199 residents were self-supplied for household water, meaning they were not on a public water system, and USGS estimated all of that self-supplied water came from fresh groundwater (USGS). That is roughly one resident in three, but it is a 2015 county-wide model estimate, not a current count or a town figure.
What the groundwater under Horry County is like
All of Horry County lies in SC DES’s Waccamaw Capacity Use Area, which sits entirely in the Outer Coastal Plain, with low relief and elevations from sea level to about 115 feet (SC DES). SC DES notes that Horry and Georgetown counties “experience frequent inundation from coastal and river flooding” (SC DES).
Under the county are layers of water-bearing sand separated by clay. The shallowest, the Surficial aquifer, is recharged directly by local rain and surface water, so its water levels rise and fall with the seasons (SC DES). Deeper Cretaceous aquifers (the Crouch Branch, McQueen Branch, Charleston and Gramling) also lie beneath the county and are recharged mainly far inland (SC DES). The report tracks large permitted wells and does not say which aquifer home wells use.
SC DES says the Waccamaw Area was set up partly because of “saltwater intrusion into wells in the North Myrtle Beach area” (SC DES), and Clemson notes that in coastal SC, saltwater intrusion may raise total dissolved solids (TDS) (Clemson Extension HGIC 1902). A 1980 USGS study also traced high natural fluoride in parts of the Black Creek aquifer system of Horry and Georgetown counties to fossil shark teeth, and linked it to dental fluorosis in people who drank the water as children (USGS).
Common well water problems
SC DES’s standard metals and minerals test for private wells checks iron, manganese, pH, hardness and several other items (SC DES), which covers most of what owners can see or taste.
Orange or brown stains: iron
Iron causes orange-brown stains and a metallic taste, and Penn State Extension recommends no more than 0.3 mg/L (Penn State Extension). Water that comes out clear and turns orange after standing holds dissolved (“reduced”) iron, which is most common in groundwater with a pH below 7.0 (Penn State Extension). More on our iron in well water page.
Black specks or stains: manganese
Manganese often travels with iron in smaller amounts and leaves black stains. The recommended limit is below 0.05 mg/L, and Penn State notes the EPA has a 0.3 mg/L health advisory for manganese (Penn State Extension).
Rotten-egg smell: hydrogen sulfide
Hydrogen sulfide comes from sulfur-reducing bacteria that thrive in low-oxygen wells and plumbing; Penn State says those bacteria “do not cause human health concerns,” though the gas can corrode metal and leave yellow or black stains (Penn State Extension). If only the hot water smells, the water heater’s magnesium rod may be the cause, and Penn State says an aluminum rod in its place should eliminate the odor (Penn State Extension). See why water smells like rotten eggs.
Blue-green stains and pinhole leaks: low pH
Clemson gives a recommended pH range of 6.5 to 8.5 and says lead and copper in well water most often come from corroding pipes and fixtures when pH is below 6.5 (Clemson Extension HGIC 1902). Penn State lists the signs: bluish-green stains in sinks, a metallic taste in the first water of the morning and small plumbing leaks (Penn State Extension).
Tea-colored water: tannins
Tannins are natural organics from vegetation that can stain water a tea color, and the Illinois Department of Public Health says they turn up more often in shallow wells or wells influenced by surface water (Illinois Department of Public Health). They can also slow iron removal, so iron filters and softeners “may not work satisfactorily” (Illinois Department of Public Health).
Scale and soap scum: hardness
Hardness is calcium and magnesium. Penn State classes 7.0 to 10.5 grains per gallon as hard and says levels below 7.0 will probably not cause major scaling (Penn State Extension).
Symptom, likely cause and usual treatment
Test first. Clemson notes that no single option treats every problem, and some wells need a “treatment train” of several steps (Clemson Extension HGIC 1903).
| What you notice | Likely cause | Usual treatment approach |
|---|---|---|
| Clear water turns orange after standing; orange stains | Dissolved iron | Oxidizing filter for moderate levels; oxidation plus filtration for high levels; a softener only for low iron in the right pH and hardness range (Penn State Extension) |
| Black specks or stains | Manganese | Oxidizing filter, or oxidation followed by filtration (Penn State Extension) |
| Rotten-egg smell in hot and cold water | Hydrogen sulfide | Activated carbon below about 1 mg/L; oxidizing filter up to 2 to 3 mg/L; chlorine or permanganate feed plus filtration for high levels (Penn State Extension) |
| Rotten-egg smell in hot water only | Water heater magnesium rod | Aluminum rod in place of the magnesium rod (Penn State Extension) |
| Blue-green stains, pinhole leaks, pH below 6.5 | Acidic, corrosive water (Clemson Extension HGIC 1902) | Acid-neutralizing filter (which adds hardness) or a soda ash feed pump (Penn State Extension) |
| Tea or yellow color | Tannins or organic iron | Treat organics first (for example activated carbon), then iron or hardness (Illinois Department of Public Health) |
| White scale, spots, poor lather | Hardness | Ion-exchange water softener, with oxidized iron filtered out first so it does not clog the resin (Penn State Extension) |
| Salty taste | High chloride, sodium or TDS | Test chloride, TDS and sodium (US EPA); reverse osmosis removes sodium and chloride (Clemson Extension HGIC 1903) |
More on matching a system to results: well water treatment in Conway.
What SC DES says about testing your well
SC DES permits and inspects the construction of new residential wells (SC DES), but it states that it “does not regulate the water quality of private wells” (SC DES). The EPA says the same nationally: private well owners are responsible for delivering safe drinking water to their households (US EPA).
How often. The EPA recommends testing every year for total coliform bacteria, nitrates, TDS and pH, and testing right away after flooding, after well repairs, or when taste, odor or color changes (US EPA). Clemson adds a comprehensive test when a well is new or has no recent results, plus a monthly check for changes in color, cloudiness, odor or taste (Clemson Extension HGIC 1902).
How. SC DES offers two kits through its regional offices and health departments: a coliform bacteria test, and a metals and minerals analysis covering alkalinity, calcium, chloride, copper, hardness, iron, lead, magnesium, manganese, nitrate/nitrite, pH and zinc (SC DES). Its lab is not accepting metals and minerals samples from June 1 to October 31, 2026, with a tentative restart on November 1 (SC DES). SC DES says these tests are not recommended for real-estate transactions, refers pesticide and volatile organic chemical testing to commercial labs, and lets private well owners apply for a PFAS assessment (SC DES).
Bacteria and nitrate need a certified lab
Bacteria and nitrate are health questions, and the EPA says to use only laboratories certified for drinking water testing (US EPA). Clemson lists septic systems, pets, livestock and wildlife as common bacteria sources, and recommends at least 75 feet between a well and a septic tank and 100 feet from a drain field (Clemson Extension HGIC 1902). For nitrate, Clemson says infants under six months who drink water above 10 mg/L could become seriously ill, and warns that boiling increases nitrate levels (Clemson Extension HGIC 1902). More in our well water testing guide.
After a hurricane or flood
SC DES says a well that was not flooded is likely unchanged. If yours was flooded, use bottled or boiled water until the well has been disinfected and tested, and test 7 to 10 days after disinfecting (SC DES). Our after-the-storm water guide walks through disinfection, testing and what to do with your treatment equipment, and the Private Well Hotline is 1-888-761-5989 (SC Department of Public Health).
Start with a free in-home screening
We offer a free in-home water test with a written report. It is a screening at your tap for common well readings such as hardness, iron, manganese, pH and dissolved solids, not a laboratory analysis. For bacteria, nitrate, lead, arsenic or PFAS, a certified laboratory test is the way to confirm. Book for Conway, Aynor, Loris or anywhere in Horry County.
Sources
- USGS: Estimated Use of Water in the United States, County-Level Data for 2015 (ver. 2.0, June 2018)
- SC DES: Waccamaw Capacity Use Area Groundwater Evaluation Report, Permitting Year 2024 (September 2023)
- USGS: Geochemistry of fluoride in the Black Creek aquifer system of Horry and Georgetown Counties, South Carolina (Water-Supply Paper 2067, 1980)
- Clemson Extension HGIC 1902: Residential Drinking Water Wells: Water Quality (October 31, 2023)
- Clemson Extension HGIC 1903: Residential Drinking Water Well: Water Treatment Options (October 31, 2023)
- SC DES: Private Drinking Water Wells
- SC DES: Well Water Quality Testing Services
- SC DES: Private Wells: What to Do Before and After Storms
- SC Department of Public Health: Water & Food Safety (storm and hurricane preparedness)
- US EPA: Protect Your Home’s Water
- US EPA: Private Drinking Water Wells
- Penn State Extension: Iron and Manganese in Private Water Systems (updated May 29, 2025)
- Penn State Extension: Hydrogen Sulfide (Rotten Egg Odor) in Water Wells (updated December 10, 2024)
- Penn State Extension: Corrosive Water Problems (updated May 29, 2025)
- Penn State Extension: Water Softening (updated September 8, 2025)
- Illinois Department of Public Health: Iron in Drinking Water (updated December 2010)
Frequently asked questions
How many people in Horry County use private wells?
A USGS estimate for 2015 put 103,189 of Horry County’s 309,199 residents on their own water supply rather than a public system, roughly one in three. It is a 2015 county-wide estimate, not a current count.
Does SC DES test or regulate my private well?
SC DES permits new residential wells but says it does not regulate the water quality of private wells. It does offer coliform bacteria and metals and minerals test kits through its regional offices and health departments; its lab has paused metals and minerals samples from June 1 to October 31, 2026.
How often should I test my well water?
The EPA recommends testing every year for total coliform bacteria, nitrates, total dissolved solids and pH, and testing right away after flooding, well repairs, or a change in taste, odor or color.
Why does my well water smell like rotten eggs?
Penn State Extension says the smell is hydrogen sulfide made by sulfur-reducing bacteria in low-oxygen wells and plumbing. If only the hot water smells, the water heater’s magnesium rod is a likely cause, and an aluminum rod should eliminate the odor.
What removes iron from well water?
Penn State Extension says oxidizing filters handle moderate iron, oxidation followed by filtration handles high levels, and a softener works only for low dissolved iron in the right pH and hardness range. A test of iron level and form comes first.
Can your free in-home test check for bacteria or nitrate?
Our free test is a screening at the tap, not a lab analysis. For bacteria, nitrate, lead, arsenic or PFAS, the EPA says to use a laboratory certified for drinking water testing.