Reverse Osmosis Systems: The Complete 1-Page Sales Guide, Sizing Workbook & Buyer’s Checklist
Want bottled-quality taste at home and data-driven clarity? This all-in-one guide shows how Reverse Osmosis (RO) works, which model to choose, how to size and install it, and how to maintain performance—plus direct links to systems, filters, membranes, tanks, and pumps on WaterSoftenerPlus.com.
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What Is Reverse Osmosis (RO)?
Reverse osmosis pushes water through a semi-permeable membrane under pressure. The membrane’s microscopic pores reject most dissolved solids (TDS), heavy metals, nitrates, fluoride, PFAS, and off-tastes. A consumer RO stack usually includes a sediment pre-filter, one or more carbon blocks, the RO membrane, and a post-carbon polishing filter. Many families add a remineralization stage for a crisp, balanced finish.
Carbon pitchers improve smell and taste; RO reliably achieves low TDS and bottled-like clarity. If your goals are clear ice, neutral taste, and gear protection, RO is your best tool.
Who Benefits Most from RO
- Taste & odor issues that persist after pitchers or fridge filters.
- TDS > 150–600+ ppm and you want bottle-like water at sink and fridge.
- PFAS, fluoride, nitrates, or lead concerns—pair carbon blocks with RO.
- Scale on espresso/coffee gear or cloudy ice with white residue.
- Aquariums / hydroponics needing a low-TDS baseline to re-mineralize precisely.
Under-Sink vs Countertop vs Whole-Home
Under-Sink RO
Best value for families: compact manifold + tank + faucet. Tee to fridge/ice for full-kitchen coverage.
Shop Under-Sink ROCountertop RO
No drilling; renter- and office-friendly. Lower output than under-sink, but ultra convenient.
Shop Countertop ROWhole-Home RO
Low-TDS water at every tap. Requires pre-softening, atmospheric storage, repressurization, and a designed concentrate line.
Shop Whole-Home ROCompare details in our Under-Sink vs Countertop RO and Whole-Home RO Planning.
Specs That Actually Matter
| Spec | Meaning | Choose | Shop |
|---|---|---|---|
| GPD (Gallons/Day) | Membrane output under standard test conditions. | Kitchens: 75–400 GPD; Commercial: 500–2,000+ GPD. | RO Membranes |
| TDS Rejection | How much dissolved solids the membrane removes. | 90–98%+ rejection; keep carbon fresh to protect the membrane. | RO Systems |
| Stages | Sediment + carbon pre-filters → membrane → post-carbon; optional remin. | 4–6 stages for kitchens; add remineralization if taste feels “flat.” | Filter Packs |
| Tank Size | On-demand buffer for fast pours. | 3.2–4.0 gal for families; larger if you cook a lot. | RO Tanks |
| Pumps | Booster/permeate pumps improve speed, recovery, and TDS stability. | Use if feed pressure < 50–60 PSI or for whole-home/commercial. | RO Pumps |
Model Spotlights & “Everything-You-Need” Bundles
Commercial Workhorse: 10,000 GPD Reverse Osmosis System
High-volume commercial RO for facilities that need serious throughput and stable low-TDS water with storage and repressurization.
Commercial Mid-Capacity: 6,400 GPD RO
Great for cafes, small breweries, and light manufacturing. Pair with mineral control where taste profiles matter (coffee, ice, tea).
Commercial Compact: ~4,800 GPD RO
Ideal for multi-station cafes and restaurants. Compact footprint with strong daily throughput.
Family Kitchen (Under-Sink • 6-Stage • 75–400 GPD)
Balanced taste, strong output, easy maintenance. Add remineralization for crisp finish and stable pH.
Apartment/Rental (Countertop • Plug-and-Pour)
No drilling. Great for offices, dorms, and short-term rentals. Lower output than under-sink, but ultra convenient.
Shop Countertop ROCoffee & Espresso (RO + Mineral Balance)
Stop scale, protect boilers, and unlock flavor clarity. Tune TDS for your brew method.
Sizing Workbook: Families, Coffee Bars & Whole-Home
A) Family Kitchen (Under-Sink)
- Daily drinking + cooking: ~1.0–2.0 gallons per person.
- Peak draw: pots/espresso/fridge—choose a 3.2–4.0 gal tank.
- Membrane: 75–200 GPD. Low feed pressure? Add a booster/permeate pump.
B) Coffee Bar (Espresso + Drip)
- Target TDS: often 75–150 ppm (taste-dependent). Use remineralization.
- Daily demand: 10–40+ gallons depending on volume.
- Recommend: 200–500 GPD chassis + remin cartridge + inline polish + TDS meter.
C) Whole-Home RO
- Pre-soften to protect membranes and improve efficiency.
- Storage design: atmospheric tank sized to peak usage (e.g., 200–500+ gal) + repressurization pump set.
- Concentrate line: plumb per code; consider reuse where allowed.
- Capacity: 1,000–2,000+ GPD depending on family size & fixtures.
Need help? See our Commercial/Whole-Home Sizing Guide.
Install: Step-By-Step + Pro Tips (Under-Sink)
- Shut off cold water; place towel/tray.
- Mount manifold where cartridges are accessible; leave room for tank.
- Install feed adapter on cold line; run tubing to RO inlet.
- Place drain saddle on vertical sink drain; drill pilot hole per kit; connect concentrate line.
- Drill faucet hole (if needed) and install RO faucet; tee to fridge/ice if desired.
- Pressurize, check for leaks, and flush 1–2 tanks before drinking.
Maintenance: Filter Schedule & Annual Cost
Change Intervals
- Sediment: 6–12 months
- Carbon blocks: 6–12 months
- Membrane: 24–36 months
- Post-carbon polish: 12 months
- Remineralization: 12 months or when taste drifts
Typical Annual Cost
Most under-sink users spend $60–$180/year on consumables. Commercial/whole-home varies with volume and water quality.
Add a TDS Meter (placeholder)Keep a spare sediment + carbon set on hand. If taste changes or flow drops, swap those first.
Troubleshooting Decision Trees (Taste, TDS, Flow, Leaks)
Tree 1: “My TDS is high”
- Just changed filters? Flush 1–2 tanks and retest.
- Measure tap TDS vs RO TDS. If rejection < 85–90%:
- Check feed pressure. If < 50–60 PSI, add a booster pump (placeholder).
- Verify flow restrictor matches membrane GPD.
- Replace carbon blocks if chlorine/chloramine breakthrough is suspected.
- Membrane older than 24–36 months? Replace membrane.
Tree 2: “Flow is slow”
- Check tank air charge (7–8 psi empty).
- Replace sediment & carbon pre-filters.
- Inspect for kinked tubing or partially closed valves.
- Low feed pressure? Add a permeate/booster pump (placeholder).
Tree 3: “Taste is off”
- Replace the post-carbon polish (placeholder).
- Add or refresh remineralization (placeholder) for balanced taste.
- Flush 1–2 tanks after any changes.
RO vs Softener (Why They Pair Perfectly)
Softener = Scale Defense
Ion exchange removes hardness to protect pipes and appliances. Not a purifier for drinking water. Perfect upstream of RO.
Shop Water SoftenersRO = Taste Clarity
Removes dissolved solids and micro-contaminants that carbon misses. For whole-home RO, a softener is strongly recommended upstream.
Shop RO SystemsRead more: Softener + RO: Best of Both
Specialty Use-Cases
Coffee & Espresso
- Run RO then remineralize to your preferred taste/TDS target (often 75–150 ppm).
- Protect boilers, reduce descaling labor, and improve flavor clarity.
Ice Makers & Fridges
Add a tee from the RO tank to your fridge line for clearer ice and better water.
RO Tee & Install PartsAquariums & Hydroponics
Start with near-zero TDS water and dose minerals precisely for species/crops.
RO Systems for Aquariums/HydroRVs & Mobile
Use countertop RO for plug-and-play, or a compact under-sink with quick-disconnects.
Countertop ROReal-World Case Studies
Case A: Family of 4, Municipal Water (TDS ~280 ppm)
Problem: Bitter taste, cloudy ice. Solution: 6-stage under-sink RO (75 GPD), 4-gal tank, remin stage. Outcome: RO TDS ~25–40 ppm, clear ice, kids drink more water.
Case B: Espresso Cart (Daily 20–30 gal)
Problem: Scale & off-flavors. Solution: 6,400 GPD RO, coffee mineral cartridge, inline polish, TDS meter. Outcome: Stable flavor, less descaling, fewer service calls.
6,400 GPD ROCase C: Whole-Home on Well
Problem: High TDS + hardness. Solution: Softener upstream + 10,000 GPD RO, atmospheric tank, repressurization, code-compliant concentrate line. Outcome: Low-TDS water at every tap, extended appliance life.
Buyer’s Checklist (Copy/Paste to Notes)
- ✔ Choose platform: Under-Sink / Countertop / Whole-Home
- ✔ Pick membrane size (GPD): 75 / 100 / 200 / 400 / 500+ (commercial)
- ✔ Add storage: 3.2–4.0 gal tank (kitchen) or atmospheric tank (whole-home)
- ✔ Confirm pressure. If < 50–60 PSI, add a booster/permeate pump (placeholder)
- ✔ Taste: remineralization (placeholder) + polish (placeholder)
- ✔ 12 months of filters: filter pack matching your system
- ✔ Add a TDS meter and fittings (placeholders above)
- ✔ Whole-home only: upstream softener, storage + pump, code-compliant concentrate line
Extended FAQ
Does RO remove fluoride, PFAS, and lead?
Yes—RO membranes plus high-quality carbon blocks reduce these effectively. Keep carbon fresh to protect the membrane. See RO Contaminant Removal.
Is RO water “too pure” to drink?
No—many love the crisp taste. If you want a more spring-like profile, add a remineralization cartridge (placeholder).
What about “waste” water?
Modern systems use efficient restrictors and pumps to improve recovery. Whole-home RO requires a designed concentrate line. Learn more in RO Recovery & Waste 101.
How often do I change filters?
Pre-filters 6–12 months; membrane 24–36 months; post-carbon & remin ~12 months. Stock a filter pack.
Can I feed my fridge/ice from RO?
Yes—tee from the RO tank to the fridge line for clearer ice and better taste. Add a permeate/booster pump if needed (placeholder link above).
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