Reverse Osmosis for Well Water — Is It Worth It?

Reverse osmosis is one of the most effective water treatment technologies available — but it is not the right solution for every well water problem. Here is what RO removes, what it doesn't, and how to decide if it makes sense for your situation.

What Reverse Osmosis Removes

Contaminant	RO Removal Rate
Nitrates	85–95%
Arsenic (As5+)	90–95%
Lead	95–99%
Fluoride	85–92%
Dissolved solids (TDS)	90–99%
Radium	85–95%
Barium	85–95%
Bacteria (with membrane intact)	99%+

What RO Does NOT Remove Effectively

• Volatile organic compounds (VOCs) — most pass through RO membranes; requires carbon block pre-filter
• Dissolved gases — hydrogen sulfide, radon, and carbon dioxide pass through
• Chlorine and chloramines — damages the RO membrane; must be pre-filtered
• Hardness — RO does reduce hardness but is not the cost-effective solution; a water softener is better
• Iron (high levels) — particulate iron clogs membranes rapidly; must be pre-filtered

Point-of-Use vs Whole-House RO

Point-of-use (under sink): $200–$500. Treats drinking and cooking water only. Most practical for the vast majority of households. Produces 50–75 gallons per day — more than enough for drinking and cooking.

Whole-house RO: $1,500–$5,000+. Treats all water in the home. Only necessary when contaminants pose skin exposure risks (some industrial VOCs, high arsenic) or when the entire household water supply is compromised. Produces significant wastewater.

RO System Maintenance

A point-of-use RO system requires:

• Pre-filters replaced every 6–12 months ($30–$60)
• RO membrane replaced every 2–3 years ($40–$80)
• Post-filter (carbon polishing) replaced annually ($15–$30)
• Total annual maintenance cost: $50–$100

When RO Makes Sense for Well Water

RO is the right choice when you have nitrates above 10 mg/L (especially with infants), arsenic above 10 μg/L, lead concerns, elevated total dissolved solids affecting taste, or multiple dissolved contaminants that would otherwise require several separate treatment systems. It is the most versatile drinking water treatment available.