TABLE OF CONTENTS
A certified under‑sink RO (with carbon pre‑/post‑filters) is built to reduce:
- Dissolved salts (TDS) & metals such as lead, arsenic, chromium, copper, sodium
- Nitrate/nitrite and fluoride (yes—RO lowers fluoride)
- PFAS ("forever chemicals")—RO is one of EPA's listed effective home treatments
- Microorganisms (parasites, bacteria, viruses) when properly maintained
- Microplastics—membrane barriers substantially reduce them
Proof standard: Look for NSF/ANSI 58 on the product label (the RO standard). Many high‑efficiency units now also carry EPA WaterSense labeling.
HOW RO WORKS
RO pushes water through a semi‑permeable membrane (~0.0001 micron). Dissolved ions and many molecules are rejected to the "concentrate" line; the "permeate" is your low‑TDS drinking water.
THE PROCESS
- •Sediment filter removes particles
- •Carbon pre-filter protects membrane
- •RO membrane rejects contaminants
- •Post-filter polishes taste
WHY IT MATTERS
- •0.0001 micron pore size blocks virtually everything
- •Carbon filters handle chlorine & taste
- •Optional remineralization for pH balance
- •NSF/ANSI 58 certification ensures performance
WHAT'S IN OUR LOCAL WATER
Understanding your water is step one. Here's what's actually in Nashville, Franklin, and Brentwood tap water—all from official Consumer Confidence Reports (CCRs).
NASHVILLE (METRO WATER SERVICES)
Cumberland River Source
- • Hardness: ~100.5 mg/L (moderately hard)
- • Chlorine residual: ~0.8–2.7 mg/L (avg 1.70)
- • Fluoride (added): ~0.68 mg/L
Disinfection Byproducts
- • TTHM LRAA: 44.8 ppb (14.2–65.3 range)
- • HAA5 LRAA: 28.7 ppb (11.5–35.8 range)
- • PFAS: Non-detect (Nov 2023)
FRANKLIN & HARPETH VALLEY (HVUD)
Blended Sources
- • Hardness: ~188 mg/L (Franklin), ~103 mg/L (HVUD)
- • Chlorine residual: ~1.2–2.2 mg/L
- • Fluoride: ~0.53–0.56 mg/L
Disinfection Byproducts
- • TTHM: ~39.9 ppb (Franklin), ~47 ppb (HVUD)
- • HAA5: ~17.3 ppb (Franklin), ~27 ppb (HVUD)
- • PFAS: Non-detect (2023–2024)
BOOK YOUR 15-MIN WATER DISCOVERY CALL
We'll have a quick 15 minute call to go over any questions you have and see if we are a fit. Serving Nashville • Franklin • Brentwood • Williamson & Davidson Counties.
WHAT RO REMOVES
Here's what NSF/ANSI 58 certified reverse osmosis systems are designed to remove from your Nashville tap water—with the local context that actually matters.
Lead, Arsenic, Chromium, Copper, Sodium
What RO does: High rejection of many ions and metals; NSF/ANSI 58 is the baseline certification (includes TDS reduction; many models also certify specific metals).
Local tie‑in: Nashville & HVUD report sodium ~8–12 mg/L (a small amount but relevant for low‑sodium diets); lead at the tap can come from home plumbing—RO at the kitchen adds protection.
What RO does: Reduces nitrate/nitrite and fluoride—both listed by CDC under RO capabilities.
Local tie‑in: Nashville & HVUD nitrate is low, fluoride is added (≈0.5–0.7 mg/L); RO lowers the level at your tap.
What RO does: EPA identifies reverse osmosis among the effective home treatments for PFAS.
Local tie‑in: Recent CCRs show non‑detect at the plant. RO provides that extra barrier at the tap.
Parasites, Bacteria, Viruses
The RO membrane pore size (~0.0001 µm) removes parasites, bacteria, and viruses when properly maintained. Municipal water is already disinfected; RO adds a point‑of‑use barrier.
Membrane Filtration
Drinking‑water treatment (including membrane processes like RO) substantially reduces microplastics; peer‑reviewed and WHO assessments support high removals.
THMs & HAA5
Activated carbon stages handle chlorine taste/odor and many DBPs. Nashville reports compliant levels: TTHM ~44.8 ppb, HAA5 ~28.7 ppb.
WHAT RO DOESN'T DO BY ITSELF (AND HOW WE HANDLE IT)
WHOLE‑HOME HARDNESS/SCALE
RO treats a drinking line. For spotting and scale on fixtures or tankless heaters, we pair a whole‑home softener/conditioner with your RO. (Local hardness ranges: ~100 mg/L Nashville; ~188 mg/L Franklin; ~103 mg/L HVUD.)
FREE CHLORINE PROTECTION
RO needs a carbon pre‑filter because thin‑film membranes tolerate <0.1 mg/L free chlorine. (Don't worry—we build this in.)
MODEL‑SPECIFIC CLAIMS
Not every RO is certified for every contaminant. Always confirm NSF/ANSI 58 and any additional contaminant claims on the performance data sheet; for PFAS, look for PFOA/PFOS claims.
OUR RO CONFIGURATION (MIDDLE TN)
STAGES
- Sediment → activated carbon (chlorine control & taste) → RO membrane
- (Optional) remineralization for taste/pH balance
CERTIFICATIONS
- We spec NSF/ANSI 58 as baseline
- Where available, we recommend WaterSense‑labeled units (≥30% efficiency; ≤2.3:1 waste‑to‑treated ratio; ≥75% TDS reduction)
MAINTENANCE
- We set reminders; pre‑filters are replaced per schedule
- Membranes last multiple years when protected
- Filter upkeep is essential for continued performance
The Bottom Line
We'll test, configure, and install a NSF/ANSI 58 system (and WaterSense‑labeled where appropriate), then keep you on schedule so performance stays like‑new.
CLEAN, GREAT-TASTING WATER—INSTALLED NEAR YOU
Nashville • Franklin • Brentwood • Williamson & Davidson Counties
FREQUENTLY ASKED QUESTIONS
Real questions from Nashville homeowners about what reverse osmosis actually removes from their tap water.
READY FOR BETTER WATER?
Book a 15-minute discovery call to discuss your water quality concerns and explore solutions—or call (615) 212-8488 for the fastest install.