Your neighbor swears by their RO system, but you've heard it strips out the good stuff along with the bad—and wastes a ton of water doing it. Here's the honest truth about what is the downside of reverse osmosis water and whether they actually matter for Nashville families.
Look, reverse osmosis isn't perfect. Like that friend who's incredibly thorough but sometimes a bit too intense, RO systems do their job almost too well. They remove everything—and I mean everything—from your water. The question is: does that create problems you should worry about?
Let's walk through the real downsides, what actually matters for your family, and better solutions that make sense for Nashville homes.
The Main Downsides of Reverse Osmosis Water
Strips Away Good Minerals
This is the big one everyone talks about, and it's absolutely true. RO membranes filter at 0.0001 microns, removing 95-99% of dissolved minerals including beneficial calcium and magnesium. Your water becomes essentially pure H2O.
Think of it like using a shop vac to clean your garage—it's incredibly effective, but it doesn't discriminate between the good stuff and the junk. That calcium and magnesium your body uses for bone health, muscle function, and dozens of other processes? Gone, along with the lead and arsenic you actually want removed.
Increases Water Waste
Traditional RO systems waste 3-4 gallons for every gallon they produce. If your family drinks a gallon of RO water per day, you're sending 3-4 gallons straight down the drain. Modern efficient systems waste only 1.5 gallons per gallon produced—much better, but still not zero.
For Nashville families paying Metro Water rates, that adds up. You're essentially buying water to throw away, which feels wasteful even when you can afford it.
Slower Fill Times
Ever tried to fill a pot from an RO faucet and felt like you're watching paint dry? Traditional tank systems can take 30+ seconds to fill an 8oz glass when the tank is low. Modern tankless systems fill that same glass in 8 seconds, but it's still slower than your kitchen tap.
When you're making coffee at 6 AM and running late, those extra seconds feel eternal.
Regular Filter Changes Required
RO systems require filter changes every 6-12 months depending on usage and water quality. Skip maintenance, and your system's effectiveness drops dramatically. Unlike your refrigerator filter that you probably forget to change, RO maintenance actually matters for performance.
Explore reverse osmosis options →
Why RO Removes Everything (Good and Bad)
How the 0.0001 Micron Membrane Works
The RO membrane is incredibly fine—imagine a net with holes so small that only individual water molecules can squeeze through. Salt molecules, bacteria, viruses, minerals, metals, and pretty much everything else gets blocked.
It's like trying to get into an exclusive club with the world's most thorough bouncer. Doesn't matter if you're Brad Pitt or a serial killer—if you're not a water molecule, you're not getting in.
What Gets Filtered Out
RO removes 95-99%+ of:
- Dissolved salts and minerals (including beneficial calcium and magnesium)
- Heavy metals like lead, arsenic, chromium, and copper
- Fluoride (85-95%)—yes, including the fluoride Nashville adds for dental health
- PFAS forever chemicals (EPA's designated "Best Available Technology" for this)
- Microplastics and microorganisms
- Chlorine byproducts like TTHMs and HAAs
That's an impressive list. The problem is it doesn't distinguish between what you want gone and what you might want to keep.
The Trade-Off: Pure but Empty
You end up with incredibly pure water that tastes "flat" to some people. That characteristic water taste comes from dissolved minerals. Remove them, and some folks describe RO water as tasting like nothing—which is technically accurate.
The Mineral Debate: Does It Actually Matter?
What Nutritionists Say About Water Minerals
Here's where it gets interesting. Most nutritionists will tell you that minerals from food sources are more bioavailable than minerals from water. You'll get far more calcium from a single glass of milk than from drinking mineralized water all day.
The World Health Organization has raised concerns about completely demineralized water, but their studies focused on extreme cases—think distilled water consumed exclusively for months. That's not how most families use RO systems.
Your Food vs Your Water for Mineral Intake
Let's put this in perspective. A banana contains more potassium than you'd get from drinking RO water with added minerals for a week. A serving of spinach delivers more magnesium than a month of mineral-enhanced water.
If you're eating a reasonably varied diet, the minerals you lose from RO water aren't likely to impact your health. If you're living on ramen and energy drinks, the water minerals aren't your biggest nutritional concern anyway.
The Taste Factor in Nashville
Nashville's moderately hard water (~6 grains) gives it a characteristic taste that some people prefer. If you grew up drinking hard water, RO water might taste weird initially. Your taste buds adapt, but some families add a remineralization stage just to make the water taste more familiar.
The flip side? If Nashville's chlorine smell bothers you, you'll love how clean RO water tastes. No more "swimming pool" smell from your drinking glass.
Water Waste: The Environmental Reality
Traditional RO Waste Ratios
Those 3-4 gallons of waste per gallon produced aren't just disappearing into the ether—they're going down your drain with all the concentrated contaminants the system filtered out. Think of it as the price of purity.
In drought-conscious areas, this matters more. Nashville gets decent rainfall, but wasting water still feels wrong to many families, especially when you're paying for it.
Modern Efficient Systems
Newer systems have improved this dramatically. Modern efficient systems now achieve 1.5:1 waste ratios, meaning you're still using more water than necessary, but it's not the 4:1 ratio of older systems.
Some manufacturers are pushing toward 1:1 ratios, but physics has limits. You need some water flow to carry away the concentrated contaminants, or your membrane gets fouled and fails early.
Nashville Water Costs Over Time
Metro Water rates aren't terrible, but the waste water adds up over time. If you're filling up water bottles and cooking with RO water regularly, factor in that extra 1.5 gallons per gallon when calculating long-term costs.
Maintenance Reality Check
Filter Replacement Schedule
Pre-filters typically need changing every 6-12 months, while the RO membrane can last 2-3 years with proper maintenance. The exact schedule depends on your water quality and usage, but there's no "set it and forget it" option.
Nashville's chlorinated water actually helps here—fewer bacteria mean less biological fouling of your filters compared to well water systems.
Annual Costs to Consider
Filter replacements aren't cheap, but they're necessary. Budget for annual filter costs when you're considering RO. A system that seems affordable upfront can get expensive if you're not prepared for ongoing maintenance.
What Happens If You Skip Maintenance
Your system doesn't just stop working—it slowly gets less effective. TDS (total dissolved solids) levels creep up, flow rates decrease, and eventually you're getting glorified tap water at RO maintenance costs.
Worse, a fouled membrane can harbor bacteria, turning your "pure" water system into a potential health risk.
RO-Only vs Whole-Home Treatment: The Missing Piece
The 60-90% Exposure You're Not Addressing
Here's something most RO companies won't tell you: drinking water only accounts for 10-40% of your yearly contaminant exposure. The other 60-90% comes through skin absorption and inhalation during showers and baths.
That means your pristine RO drinking water is addressing less than half your family's total exposure to chlorine, TTHMs, and other contaminants. You're still breathing chlorine vapor every time someone showers and absorbing it through your skin during baths.
Why Nashville Water Needs Both Approaches
Nashville uses chloramine—like chlorine's angry big brother—which is harder to filter and creates its own set of byproducts. TTHMs average 44.8 ppb in Nashville water, which is 90-100x above EWG health guidelines despite being legal.
An RO system at your kitchen sink gives you pure drinking water. But you're still showering in the same water that created those white spots on your dishes and left your skin feeling dry.
Cost Comparison: RO vs Full System
Whole-home RO costs $16,000+ and is complete overkill for Nashville's municipal water. You don't need RO-level filtration for washing dishes or watering plants.
A smarter approach: whole-home carbon filtration plus RO at the kitchen sink gives you nearly all the benefits at a fraction of the cost.
Better Solutions for Nashville Homes
Whole-Home Carbon + RO Combination
This is what we actually recommend for most Nashville families: a single-tank combo system with ion exchange resin and catalytic carbon for the whole house, plus RO at the kitchen sink for drinking water.
The whole-home system handles hardness, chlorine, and chloramine for every tap. The RO system gives you ultra-pure drinking water. You get the best of both worlds without the waste and expense of whole-home RO.
When RO Makes Sense vs Overkill
RO makes sense if:
- You have specific health concerns requiring ultra-pure water
- You're dealing with contamination that only RO can handle (like PFAS)
- You want the absolute purest drinking water possible
- You don't mind the maintenance and waste
RO might be overkill if:
- Nashville's treated water is your only concern
- You're mainly worried about hardness and chlorine taste
- Budget is a primary consideration
- You want a low-maintenance solution
What We Actually Recommend
For most Nashville families: whole-home treatment that removes hardness and chlorine from every tap, plus RO at the kitchen sink for drinking water. This addresses 100% of your water exposure, not just the 10-40% you drink.
It costs less than whole-home RO, requires less maintenance than multiple point-of-use systems, and gives you better results for daily living—softer skin, cleaner dishes, and pure drinking water.
Explore whole-home solutions →
Making the Right Choice for Your Family
Questions to Ask Before Installing RO
Before you invest in RO, ask yourself:
- What specific contaminants am I trying to remove?
- Am I addressing my full water exposure or just drinking water?
- Do I understand the ongoing maintenance requirements?
- Is the water waste acceptable for my situation?
- Would a less intensive solution solve 90% of my concerns?
Alternatives to Consider
Depending on your specific concerns:
- Carbon filtration handles chlorine, taste, and odor issues
- Water softening eliminates hardness problems
- Whole-home treatment addresses system-wide issues
- Combination systems give you multiple benefits in one install
Getting Your Water Actually Tested
Here's the thing about water treatment: you can't fix what you don't measure. Nashville's water quality varies by neighborhood and season. What works in Belle Meade might be overkill in Green Hills.
Get your specific water tested so you know what you're actually dealing with. Then you can choose a solution that fits your water, your family, and your budget.
Frequently Asked Questions
The Bottom Line
RO water has downsides—it removes beneficial minerals, wastes water, and only addresses part of your family's total water exposure. But for Nashville families dealing with specific contaminants or wanting the purest possible drinking water, these trade-offs might be worth it.
The key is understanding that RO isn't a magic solution for all water problems. It's one tool that works best as part of a comprehensive approach to your home's water quality.
Most Nashville families get better results from whole-home treatment that addresses hardness and chlorine system-wide, plus RO at the kitchen sink for drinking water. You solve the real problems affecting your daily life while getting ultra-pure water where it matters most.
Stop fighting your water. Start enjoying it. The right combination of treatments can give you everything you want without the compromises you don't.
Share this article
