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Jan 30, 2019·8 min read
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All You Need To Know About A 5 Stage Reverse Osmosis System – AMPAC USA

Sammy FaragAMPAC USA — January 30, 2019

All You Need To Know About A 5 Stage Reverse Osmosis System – AMPAC USA

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Quick Answer: A 5-stage reverse osmosis system includes: Stage 1 (sediment filter, 5 micron), Stage 2 (carbon block filter), Stage 3 (second carbon filter), Stage 4 (RO membrane, 0.0001 micron, removes 95-99% of dissolved solids), Stage 5 (post-carbon polishing filter). This configuration removes sediment, chlorine, VOCs, heavy metals, dissolved salts, nitrates, fluoride, and most other regulated contaminants.

Even in the world of reverse osmosis, there are technologies that give the best results even in the most pollutes waters. A 5 Stage RO water system is by far the most advanced water technology that provides H2O of the utmost superior quality. And why not? It covers almost every impurity known to man and gets it out for safe and quality drinking water.

Reverse Osmosis
The process is an unchallenged champion in purifying water. Since the last few decades, it has proven outcomes to show for its credibility. Using the natural process of osmosis and reversing it for purification was probably the best technological advancement of the 20th century. With an effectiveness of 99%, the process still amazes the industry with its scope and improvements. For a few years now the process is being aided to be able to deal with any kind of impurity which reflects the use of a 5 Stage RO.

What is a 5 Stage RO?
As the name suggests, this particular reverse osmosis system has a total of 5 stages, each stage responsible to make your water better.

Sediment filter: Made of polypropylene, this filter is responsible to take out major impurities that plague the water. Soil, dust, dirt, small pebbles even rust. The filter takes care of impurities over 5 microns.
Carbon filter: Granulated activated carbon is used to filter out chlorine a positively charged elements. This helps to eliminate bad odor and taste of the water.
Second polypropylene layer: This is an extra stage added to the system in case the sediment filter is not enough. It is responsible for eliminating impurities up to 1 micron. This clears out any remaining sediments.
Osmotic membrane: This is where all the major action happens. Water is passed through the semi-permeable membrane that removes fluoride, organic and inorganic compounds, total dissolved salts and more. This gives pure and safe drinking water after purification.
Second carbon filter: A second carbon filter is added to remove the bad taste which comes after the osmotic membrane. Many times this stage is replaced by remineralization filters that add essential calcium and magnesium minerals that are eliminated in the process.

When should this RO be used?
This RO is used for household purposes majorly in areas near factories, brackish sources or coasts. It is because the water obtained in those areas have a high level of impurity and require only the most advanced RO for purification. This is also preferred in aquariums, offices, restaurants, labs, and institutions due to its quality. It boasts of a 99% efficiency in removing various contaminants like chlorine, fluoride, TDS, mercury, microorganisms, lead, cadmium and chromium In the market, no other machine beats the standard Ampac 5 Stage RO water system which comes with quality results and after sale service. If you require an RO for your home, visit Ampac today!

Author’s Bio:
Ampac USA is a leading manufacturer of advanced reverse osmosis water treatment systems. For over 30 years the company has been providing its customers and clients around the world solutions to their water treatment problems. With years of an impressive track record, Ampac strives to develop solutions to make reverse osmosis systems, advanced for improved quality and cost efficiency.

What is the typical lifespan of an RO membrane?

High-quality RO membranes last 2–5 years depending on feed water quality and maintenance frequency. AMPAC USA systems use thin-film composite (TFC) membranes rated for extended service life. Regular pre-filter replacement and periodic membrane cleaning significantly extend operational longevity.

How much water does an RO system waste?

Standard RO systems recover 50–75% of feed water as permeate (purified output), with the remainder discharged as concentrate. AMPAC USA's high-recovery commercial systems achieve up to 85% recovery using energy recovery devices and optimized flow design, reducing operational costs substantially.

What pressure is required for a reverse osmosis system?

Brackish water RO systems typically operate at 150–600 PSI, while seawater systems require 800–1,200 PSI. AMPAC USA designs each system to match source water salinity and desired flow rate, incorporating energy-efficient high-pressure pumps with variable frequency drives (VFDs) to minimize power consumption.

Can reverse osmosis remove viruses and bacteria?

Yes. RO membranes provide absolute removal of bacteria (>99.9999%) and viruses (>99.99%), making them one of the most effective water purification technologies. AMPAC USA systems exceed NSF/ANSI 58 standards and include pre-treatment stages to protect membrane integrity.

Conclusion

This post explored how reverse osmosis technology delivers high-purity water across a wide range of residential, commercial, and industrial applications. For businesses and organizations requiring reliable RO purification, AMPAC USA engineers custom systems tailored to your specific water quality requirements and flow demands. Contact our team at [email protected] or (909) 548-4900 to discuss your water treatment needs.

5-Stage Reverse Osmosis: Stage-by-Stage Function and Maintenance

The 5-stage reverse osmosis system is the most widely used residential water treatment configuration, providing comprehensive contamination reduction at the point of use for drinking and cooking water. Each stage has a specific function and contaminant target, and the sequential arrangement ensures that each component is protected by the stages before it — extending service life and maintaining consistent performance throughout the system’s operational period.

Stage 1 (sediment filter, 5-10 micron): Removes suspended particles, sand, rust, silt, and sediment. This stage protects all downstream components from physical damage and clogging. Sediment filters require replacement every 3-6 months depending on source water turbidity. A 1-micron absolute sediment filter in Stage 1 is preferred for well water with fine sediment. Stage 2 (carbon block filter, 5 micron): Removes chlorine, chloramines, VOCs, pesticides, and organic contaminants that would otherwise chemically degrade the delicate polyamide RO membrane in Stage 4. This stage also begins improving taste and odor. Stage 3 (second carbon block or GAC): Provides additional chlorine and organic compound removal capacity, ensuring complete dechlorination before the membrane. Some systems use a granular activated carbon (GAC) stage here for cost reduction.

Stage 4 (RO membrane, 0.0001 micron): The core separation stage. Under household water pressure (40-80 PSI), water is forced through the polyamide thin-film composite membrane. Approximately 95-99% of dissolved solids are rejected, including heavy metals (lead, arsenic, barium, cadmium, chromium), TDS, fluoride, nitrates, radium, and most pharmaceuticals and PFAS. Product water flows to the storage tank; concentrated reject water drains. Stage 5 (post-carbon polishing filter, 0.5 micron): Removes any residual taste or odor from the storage tank before water reaches the dispense faucet. This final stage ensures consistently fresh-tasting water. Optional Stage 6 (UV) adds microbial disinfection for well water or any application where bacterial safety is a concern. AMPAC USA residential systems are available in both standard and enhanced configurations.

Frequently Asked Questions

Q: How does a 5-stage RO system differ from a 3-stage system?

A: A 3-stage system typically uses one carbon pre-filter, an RO membrane, and one post-carbon filter. A 5-stage system adds a dedicated sediment filter and a second carbon stage, providing better membrane protection, improved organic removal, and longer membrane service life.

Q: How long does a 5-stage RO system last?

A: With proper maintenance, the system housing and components last 10-15+ years. Sediment and carbon pre-filters require replacement every 6-12 months. The RO membrane lasts 2-5 years. The post-carbon polishing filter should be replaced every 12 months. The pressure vessel (tank) typically lasts the life of the system.

Q: What TDS should 5-stage RO water measure?

A: A properly functioning 5-stage RO system should produce water with less than 50 ppm TDS from typical municipal feed water. If product water TDS exceeds 10-15% of feed water TDS, the RO membrane may need cleaning or replacement. A basic TDS meter ($15-25) allows easy performance monitoring.

Q: Does a 5-stage RO system remove fluoride?

A: Yes. Standard TFC polyamide RO membranes reject fluoride at 85-95% efficiency. Some fluoride will pass through at very low concentrations. If fluoride-free water is the specific goal, verify your system's NSF Standard 58 certification for fluoride reduction.

Q: How much water pressure does a 5-stage RO system need?

A: Minimum 40 PSI inlet pressure is required for adequate RO membrane performance. Optimal production is at 50-80 PSI. Below 40 PSI, a booster pump (permeate pump or electric pressure booster) is recommended to maintain adequate flux through the membrane.

Q: Is the reject (waste) water from an RO system actually contaminated?

A: No — RO reject water is concentrated tap water, not contaminated waste. It contains higher concentrations of the minerals present in your tap water. It is safe for watering non-edible plants, toilet flushing, or cleaning. High-efficiency RO systems reduce reject ratios to 1:1 from the traditional 3-4:1.

Q: What is the storage tank in a 5-stage RO system?

A: The pressurized storage tank (typically 3-4 gallons capacity) stores pre-treated RO water ready for dispensing. It uses a bladder and pressurized air charge to maintain output pressure. The tank should be drained and sanitized annually as part of system maintenance.

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