Reverse Osmosis (RO) is the gold standard for drinking water filtration. While a water softener protects your home's plumbing, an RO system protects your body by removing up to 99% of dissolved contaminants from your tap water.
The 5-Stage RO Process
Most quality RO systems use a multi-stage approach to purify water:
- Sediment Filter: Removes dirt, rust, and silt to protect the delicate RO membrane.
- Pre-Carbon Filter: Removes chlorine and chloramines (which Denver uses) that can destroy the RO membrane.
- Second Carbon Filter (Optional): Further ensures all chlorine is removed.
- The RO Membrane: The heart of the system. Forces water through microscopic pores, removing heavy metals, fluoride, lead, arsenic, and dissolved solids.
- Post-Carbon Filter: A final "polishing" filter that removes any residual tastes or odors before the water reaches your glass.
What RO Removes from Denver Water
Denver Water generally meets all EPA safety standards, but an RO system provides peace of mind by removing:
- Total Dissolved Solids (TDS): Denver's water typically runs between 280-340 ppm TDS. RO reduces this to near zero.
- Chloramines: Denver Water uses chloramines (chlorine + ammonia) for disinfection. RO systems equipped with catalytic carbon effectively remove this.
- Fluoride: Denver Water adds fluoride. RO is one of the only ways to remove it.
- Trace Nitrates & Heavy Metals: Removes potential contaminants picked up through older city distribution pipes.
Under-Sink vs Whole-House RO
99% of homeowners only need an Under-Sink (Point-of-Use) system. It purifies the water at a single dedicated faucet in the kitchen and often connects to the refrigerator ice maker.
Whole-House RO systems purify every drop of water entering the home. They are extremely expensive ($5,000 - $15,000+), require massive storage tanks, and typically require you to re-mineralize the water before it enters your copper pipes (as pure RO water is slightly acidic and can corrode copper). We rarely recommend whole-house RO in Denver.
Costs and Maintenance
- System Cost: $200 - $600 for a quality under-sink unit.
- Installation: $150 - $300 (or DIY friendly for handy homeowners).
- Maintenance: Expect to spend $50 - $150 annually. Pre/post filters should be changed every 6-12 months. The main RO membrane typically lasts 2-3 years.
Top RO Brands
APEC: Industry standard, widely available, uses standard non-proprietary filters (cheaper replacements).
iSpring: Similar to APEC, great customer service, many options including remineralization stages.
Waterdrop: Known for modern, "tankless" designs that save space and waste less water.
Aquasana: Premium systems, often NSF certified for specific contaminant removal.
The Water Waste Reality
Traditional RO systems waste water to make water. The membrane needs flowing water to flush away the rejected contaminants. Older systems might waste 3-4 gallons of water for every 1 gallon of purified water produced.
Denver Recommendation: Look for systems with a "permeate pump" or modern "Tankless" designs. These can improve the ratio to 1:1, saving thousands of gallons of water per year—an important consideration in Colorado.