Well Water Treatment System: Match Test Results to a Fix
Choose a well water treatment system from your lab report: thresholds and the right technology for 11 common problems, plus installer and upkeep tips.
Pick a well water treatment system from your lab report, not from a product page. Find each result that exceeds its threshold, match it to the technology in the table below, and fix the source first if you can, such as a cracked well cap or a nearby septic line. MDH notes that no single unit removes everything, so a well with several problems needs several stages. The whole house water filter hub shows the order to plumb them in.
If you don’t have a recent lab report, start with well water testing. UGA Extension recommends testing bacteria and nitrate every year.
Problem → treatment matrix
| Test result | Threshold (source) | Treatment technology | POE or POU | Read more |
|---|---|---|---|---|
| Total coliform / E. coli | Should be absent (UGA B 939) | Shock chlorination, then continuous chlorination or NSF 55 Class A UV if it returns | POE | Coliform, UV |
| Nitrate | 10 mg/L as nitrogen (EPA MCL) | Reverse osmosis or distillation for drinking water; anion exchange for the whole house | POU (RO), POE (anion) | Nitrates, RO |
| Arsenic | 10 µg/L (EPA MCL; MDH action level) | Adsorptive media (iron or titanium based), RO, anion exchange, oxidation filtration | POE or POU | RO |
| Iron / manganese | 0.3 mg/L Fe, 0.05 mg/L Mn (EPA secondary) | Softener (low dissolved iron), greensand or other oxidizing filter, chlorination plus filtration at high levels | POE | Iron hub, Iron removal |
| Hydrogen sulfide | Most people smell it well below 0.5 mg/L (Penn State) | Carbon below about 1 mg/L; greensand up to about 2–3 mg/L; chlorination or permanganate above 6 mg/L | POE | Sulfur smell |
| Low pH | Below 6.5 (EPA secondary range 6.5–8.5) | Calcite or magnesium oxide neutralizer; soda ash feed pump | POE | Acid neutralizers |
| Hardness | About 7 gpg (about 120 mg/L) interferes with soap (UGA) | Cation-exchange softener | POE | Water softeners |
| Sediment / turbidity | Above 5 NTU suggests possible bacteria (UGA); above 1 NTU needs pretreatment before UV (UConn) | Cartridge or backwashing sand filter | POE | Sediment filters |
| Tannins | Yellow-brown color (no EPA health standard) | Anion exchange above pH 6; activated carbon below pH 5 (WQA) | POE | Filtration systems |
| Radon | No federal standard (EPA); consider action above 4,000 pCi/L (Wisconsin DNR) | Aeration; granular activated carbon | POE only | Filtration systems |
| PFAS (PFOA, PFOS) | 4.0 ng/L each (EPA MCL for public systems) | Granular activated carbon, RO, ion exchange certified to NSF/ANSI 53 or 58 | POU or POE | RO |
Notes the table can’t hold
Bacteria
UGA recommends finding and removing the contamination source first: surface water at the casing, a septic line too close to the well, or livestock runoff. Then shock chlorinate. Use continuous disinfection only if coliform comes back. Colorado State Extension notes that chlorination leaves a residual in the plumbing and UV does not. UGA advises against UV when untreated water exceeds 1,000 total coliform or 100 fecal coliform per 100 mL.
Nitrate and arsenic
Neither one responds to boiling. MDH warns that boiling concentrates both. A conventional softener doesn’t remove nitrate or arsenic, and MDH adds that carbon alone won’t remove arsenic either. MDH also recommends that babies under 6 months not drink the well water even after nitrate treatment. UGA notes that some RO units are certified only for arsenic V and not arsenic III, so check the certification listing for the form your lab reported. UGA also warns that anion exchange can leave water corrosive, so it may need a neutralizer after it.
Iron, manganese and hydrogen sulfide
Penn State’s limits:
- Softener: dissolved iron below 5 mg/L, at pH above 6.7 and hardness of 3 to 20 gpg.
- Greensand: about 3 to 10 mg/L of combined iron and manganese.
- Above 10 mg/L combined: oxidation followed by filtration.
If the rotten-egg smell shows up only in hot water, Penn State points to the water heater’s magnesium anode, which an aluminum rod usually fixes without any treatment equipment.
Low pH
Virginia Tech Extension notes that neutralizer media dissolves into the water and adds hardness, so a softener may be needed after it. UGA lists soda ash feed as the alternative. UGA notes it can share a feed pump with chlorine when disinfection is also needed.
Radon and PFAS
Wisconsin DNR calls aeration the most effective radon treatment. It describes GAC as effective, but spent carbon from water at 4,000 pCi/L or higher can hold hazardous radiation levels. Small faucet or under-sink filters are inadequate for radon. UGA notes that RO doesn’t remove dissolved gases, radon included. For PFAS, EPA says certifications currently focus on PFOA and PFOS, and filters only work when they’re replaced on the manufacturer’s schedule.
How to pick an installer
- Check the license. Minnesota requires a licensed plumbing or water conditioning contractor for installs. Other states differ, so ask your county health department.
- Verify certification. MDH points buyers to units certified by NSF, UL or WQA for the specific contaminant. Look the model up in the certifier’s listing yourself. UGA warns that “tested to NSF standards” wording is not proof of certification.
- Get two quotes. UGA advises comparing at least two dealers and brands, checking references, and having a qualified person review your results before you buy. In-home tests can’t measure arsenic, uranium or organics.
- Put the follow-up test in writing. UGA recommends a written guarantee tied to a water test about 1 to 2 months after installation.
- Ask about total cost. That means installation, salt and media, electricity, cartridges, RO reject water, and whether doing your own maintenance voids the warranty.
- Check the plumbing details. Minnesota’s rule requires isolation and bypass valves on every water conditioning install and an air gap where backwash water enters the drain.
Maintenance schedule
| Task | Interval | Source |
|---|---|---|
| Test treated water for bacteria and nitrate | Every year | UGA B 939; MDH |
| Follow-up test after a new install | About 1–2 months after | UGA B 939 |
| Replace the UV lamp | Every 9–12 months | Colorado State |
| Test water after UV for bacteria | Periodically, to verify performance | UGA B 939 |
| Replace the sediment cartridge | When clogged; don’t leave a spent cartridge in place | UGA B 939 |
| Replace the carbon media or cartridge | At the manufacturer’s capacity; spent carbon can grow bacteria | UGA B 939; UConn |
| Regenerate greensand with potassium permanganate | When oxidizing capacity drops | Penn State; UGA B 939 |
| Backwash and top up neutralizer media | As the bed dissolves; the rate depends on pH and water use | Virginia Tech; UGA B 939 |
| Mix fresh chlorine stock solution | At least weekly | UGA B 939 |
| Replace the RO membrane and prefilters | On the manufacturer’s schedule; test before and after RO | UGA B 939 |
| Fill the softener brine tank with salt | As the manufacturer directs | UGA B 939 |
MDH warns that units that aren’t maintained lose effectiveness and can make water quality worse. Write the intervals on the equipment and add a reminder to your calendar.
Choosing the hardware
Once you know which stages you need, compare packaged well water filtration systems. Add UV for bacteria, a sediment filter ahead of everything, and reverse osmosis at the kitchen tap for nitrate, arsenic or PFAS.
Sources
- EPA — National Primary Drinking Water Regulations
arsenic 0.010 mg/L; nitrate 10 mg/L as N; PFOA and PFOS 4.0 ng/L (public systems) - EPA — Secondary Drinking Water Standards
iron 0.3 mg/L; manganese 0.05 mg/L; pH 6.5–8.5 - University of Georgia Extension — Water Quality and Common Treatments for Private Drinking Water Systems (B 939)
coliform absent; UV limits of 1,000 total / 100 fecal coliform per 100 mL; arsenic media; nitrate options; hardness 7 gpg; turbidity 5 NTU; dealer checklist; maintenance; test intervals - Minnesota Department of Health — Arsenic in Well Water
act above 10 µg/L; softeners and carbon alone don't remove arsenic; licensed installer - Minnesota Department of Health — Nitrate in Well Water
don't boil; test yearly; infants under 6 months - Minnesota Department of Health — Home Water Treatment
certification by NSF, UL or WQA; licensed plumber or water conditioning contractor; test after install - Minnesota Rules 4714.0611 — Water conditioning equipment
isolation and bypass valves; air-gap discharge; NSF/ANSI 61 materials - Penn State Extension — Iron and Manganese in Private Water Systems
technology by mg/L of iron and manganese - Penn State Extension — Hydrogen Sulfide (Rotten Egg Odor) in Water Wells
odor below 0.5 mg/L; technology by mg/L band; anode rod - Colorado State University Extension — Bacteria in Water Wells
UV has no residual; UV lamp every 9–12 months - UConn Extension — Managing Your Private Well, Water Treatment Guide
UV pretreatment above 1 NTU; carbon and RO for PFAS - Water Quality Association — Glossary of Terms (Tannin)
anion exchange above pH 6; activated carbon below pH 5 - Wisconsin DNR — Radon in Private Well Water
consider action above 4,000 pCi/L; aeration and GAC; POU filters inadequate - EPA (archive) — Radon in Drinking Water Questions and Answers
no federally enforced radon standard - EPA — PFAS in Private Wells
GAC, RO, ion exchange; NSF/ANSI 53 or 58 - Virginia Tech Extension — Household Water Treatment (442-670)
neutralizers add hardness; media replenishment