Reverse Osmosis for Well Water: Complete Guide
Quick Answer: RO removes 95-99% of contaminants from well water, producing near-pure drinking water. Best used at point-of-use (kitchen sink) rather than whole-house due to waste water. Typical cost: $200-$500 under-sink installed. Pre-filtration required for most well water. Annual filter costs: $50-$150.
How Reverse Osmosis Works
The Process
- Pre-filters remove sediment and chlorine
- Water is pressurized against semi-permeable membrane
- Pure water molecules pass through membrane
- Contaminants are rejected and flushed to drain
- Purified water stored in tank
- Post-filter polishes taste before dispensing
Typical Stage Configuration
- Stage 1: Sediment filter (5 micron)
- Stage 2: Carbon block (removes chlorine, organics)
- Stage 3: RO membrane (the main work)
- Stage 4: Post carbon (taste polishing)
- Stage 5: Some add remineralization
Waste Water
- RO produces waste water (concentrate)
- Typical ratio: 2-4 gallons waste per 1 gallon pure
- Higher efficiency units: 1:1 ratio possible
- Waste goes to drain (or can be used for plants)
What RO Removes
Highly Effective (95-99% removal)
- Total dissolved solids (TDS)
- Sodium
- Nitrates
- Arsenic
- Lead
- Fluoride
- Chromium
- Bacteria and parasites
Also Removes
- Hardness (calcium, magnesium)
- Iron
- Sulfates
- Pesticides
- Many pharmaceuticals
May Not Fully Remove
- Some volatile organic compounds (VOCs)
- Dissolved gases
- Some pesticides (need carbon pre-filter)
The Result
RO produces near-pure water. TDS typically drops from 200-500+ to under 50. Tastes clean and neutral.
RO for Well Water Specifically
Pre-Treatment Usually Required
- Sediment: Clogs membrane quickly
- Iron: Fouls membrane (remove first if above 0.3 ppm)
- Hardness: Can scale membrane (softener helps)
- Bacteria: RO removes, but UV or chlorine before RO is safer
Ideal Setup for Well Water
- Sediment pre-filter
- Carbon pre-filter (if any organics/taste issues)
- Iron filter (if iron present)
- Water softener (if hard water)
- RO system at drinking water tap
When RO Makes Sense for Wells
- Nitrate contamination (RO removes it)
- Arsenic or heavy metals
- High TDS affecting taste
- Want purest possible drinking water
- Municipal water isn't available
When RO May Be Overkill
- Well water already tests clean
- Only issue is hardness (softener is enough)
- Only issue is bacteria (UV is cheaper)
System Types
Under-Sink (Point-of-Use)
- Most common for residential
- Treats drinking/cooking water only
- Separate faucet at sink
- Storage tank under sink
- Cost: $150-$600
Countertop
- No installation required
- Connects to faucet
- Portable
- Smaller capacity
- Cost: $150-$400
Whole-House RO
- Treats all water entering home
- Large system with storage tank
- High initial and operating cost
- Significant waste water
- Usually only for severe contamination
- Cost: $1,500-$5,000+
Tankless RO
- No storage tank, produces on demand
- Faster flow, fresher water
- More efficient (less waste)
- Higher upfront cost
- Cost: $300-$800
Maintenance
Filter Replacement Schedule
| Filter | Frequency | Approximate Cost |
|---|---|---|
| Sediment pre-filter | Every 6-12 months | $5-$15 |
| Carbon pre-filter | Every 6-12 months | $10-$25 |
| RO membrane | Every 2-3 years | $50-$100 |
| Post carbon | Every 12 months | $10-$20 |
Signs Filters Need Replacing
- Slower water production
- Taste changes
- TDS readings increase
- Visible discoloration
Tank Maintenance
- Check air pressure annually
- Sanitize tank periodically
- Replace tank every 10-15 years
Testing
- Use TDS meter to verify performance
- Should reduce TDS by 90%+
- Test periodically to catch membrane degradation
Costs
Equipment
| Type | Cost |
|---|---|
| Basic under-sink | $150-$300 |
| Quality under-sink | $300-$500 |
| Premium/tankless | $400-$800 |
| Whole-house | $1,500-$5,000 |
Installation
- Under-sink DIY: $0
- Under-sink professional: $100-$300
- Whole-house: $500-$2,000
Annual Operating
- Filter replacements: $50-$150
- Additional water (waste): minimal cost
- Membrane replacement (prorated): ~$30/year
Total First Year
- Under-sink: $300-$800
- Whole-house: $2,000-$7,000
Frequently Asked Questions
Is reverse osmosis good for well water?
Yes, RO removes 95-99% of contaminants. Pre-treatment is usually needed for well water to protect the membrane.
How much does a reverse osmosis system cost?
Under-sink: $150-$600. Installed with quality system: $300-$800. Whole-house: $1,500-$5,000+.
Does RO waste a lot of water?
Traditional systems waste 2-4 gallons per gallon produced. High-efficiency systems can achieve 1:1 ratio.
Is RO water safe to drink?
Yes, completely safe. Some people add minerals back for taste. RO removes contaminants, not safety.
How long does an RO system last?
Quality systems last 10-15 years with proper filter maintenance. Membrane is key component.
Do I need RO if I have a water softener?
Softeners only remove hardness. RO removes dissolved solids, nitrates, arsenic, etc. Different purposes—some use both.
Want Pure Drinking Water?
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