Hydrogen sulfide levels: which treatment system fits your number
The right sulfur-water system depends mostly on how much hydrogen sulfide is in your water. Penn State Extension: “The most efficient and cost-effective treatment option will depend primarily on hydrogen sulfide concentration.”1 So get a number before you get a quote.
Step 1: Get an H2S measurement
- H2S must be tested in the home, or the sample must be chemically stabilized before going to a lab.1
- UF/IFAS: for bad smell or taste, test for hydrogen sulfide, corrosivity, copper, lead and pH.2 To find a certified lab, use the FDEP NELAP certified lab search. Some county health departments also offer testing.2
- Most people can smell H2S at well below 0.5 mg/L (1 mg/L ≈ 1 ppm in water).1
Step 2: Match the level to a treatment
| H2S level | Options named by Penn State Extension | Notes from the source |
|---|---|---|
| Below about 1.0 mg/L | Whole-house activated carbon | Usually 1.0–1.5 cu ft of carbon. Low cost and maintenance, but the carbon needs periodic replacement.1 |
| Up to about 2 mg/L | Aeration | No chemicals added. Low maintenance cost but often a higher purchase price. Not usually used above ~2 mg/L. Disinfecting aerated water is recommended.1 |
| Higher levels | Catalytic carbon or a manganese greensand oxidizing filter | Catalytic carbon handles “much higher” levels than plain carbon. Greensand needs regenerating with potassium permanganate and regular backwashing. Penn State says Birm media is not recommended for H2S.1 |
| Above about 6.0 mg/L | Continuous chlorination + filtration, or potassium permanganate injection + greensand | Chlorination works at any level but is most often used above 6.0 mg/L, with at least 20 minutes of contact time. Carbon may be needed afterward to remove the chlorine taste. Permanganate needs about 15 minutes of contact, and the chemical is “an irritant and poison.”1 |
What about shock chlorination?
UF/IFAS calls shock chlorination the most common treatment method for well H2S.2 But Penn State notes that “in most cases, sulfur-reducing bacteria and hydrogen sulfide odor will return quickly after shock chlorination.” If the relief doesn’t last, look at a continuous system from the table.1
Before you buy
Penn State’s advice: compare units and prices among several reputable dealers, understand the maintenance each unit needs, and get a written warranty.1 If a dealer can’t tell you which H2S level their system is rated for, keep shopping.
Hot water only? Try the anode rod fix first. Not sure where the smell starts? Use the diagnosis guide.