What is Ro?

Reverse Osmosis Water Purification

Reverse osmosis, also known as hyperfiltration, is the finest filtration available today.
It is the most common treatment technology used by premium bottled water companies.
It is effective in eliminating or substantially reducing a very wide array of contaminants,
and of all technologies used to treat drinking water in residential applications, it has the greatest range of contaminant removal.
Reverse osmosis will allow the removal of particles as small as individual ions.
  1. The pores in a reverse osmosis membrane are only approximately 0.0005 micron in size (bacteria are 0.2 to 1 micron & viruses are 0.02 to 0.4 microns).
There are two types of reverse osmosis membranes commonly used in home water purification products: Thin Film Composite (TFC) and Cellulose Triacetate (CTA).
TFC membranes have considerably higher rejection rates (they will filter out more contaminants) than a CTA membrane, however, they are more susceptible to degradation by chlorine.
This is one of the reasons why it is important that a reverse osmosis system include quality activated carbon pre-filters.
A typical RO system is composed of an array of granular activated carbon (GAC) pre-filters, the reverse osmosis membrane, a storage tank, and a faucet to deliver the purified water to your countertop.
Reverse osmosis systems vary in membrane quality, output capacity, and storage capacity.
Reverse osmosis, is known as Hyper filtration the process allows removal of particles as small as ions from solution. R.O is a membrane based desalination process that use semi permeable membrane and based on principle of reverse osmosis. It can reject up to 95% of dissolved salts and almost all organics, heavy metals, & even micro organism. This water treatment technology is widely used all over the world for purified water while rejecting concentrated dissolved & suspended solids. This membrane mould collects the purified water in a permeate tube. The most common use for reverse osmosis process is in the purification of water.
 
How it Works
 
Reverse osmosis uses a membrane that is semi-permeable, allowing pure water to pass through it, while rejecting the contaminants that are too large to pass through the tiny pores in the membrane. Quality reverse osmosis systems use a process known as cross flow to allow the membrane to continually clean itself. As some of the fluid passes through the membrane the rest continues downstream, sweeping the rejected contaminants away from the membrane and down the drain. The process of reverse osmosis requires a driving force to push the fluid through the membrane (the pressure provided by a standard residential water system is sufficient - 40 psi ).
Reverse Osmosis Water Filtration
 
Applications
 
Reverse osmosis is an excellent choice for almost all home water purification needs. It is the most recommended solution for individuals on a pre-treated municipal water system. While reverse osmosis can be very effective in removing bacteria and viruses, it is not recommended that reverse osmosis be the only level of purification for water that contains or may contain biological contaminants (untreated well or lake water, for instance). For these applications consider a combined reverse osmosis / ultraviolet system or the addition of a complementary whole-house ultraviolet system for maximum effectiveness and protection against bacteria and viruses. Since membranes are subject to degrading by chlorine, iron, manganese, and hydrogen sulfide, and to bacterial attack, a sediment pre-filter and an activated carbon pre-filter and/or post-filter should be included with your reverse osmosis system. Water softeners can be used in advance of the RO system when household water is excessively hard to prevent pre-filter and membrane fouling. RO systems are generally the best choice for water contaminated with high nitrite levels as might be found in agricultural areas.
What Contaminants Does Reverse Osmosis Remove?
Reverse osmosis (RO) units remove substantial amounts of most inorganic chemicals (such as salts, metals, minerals) most microorganisms including cryptosporidium and giardia, and most (but not all) inorganic contaminants.
Reverse osmosis successfully treats water with dissolved minerals and metals such as aluminum, arsenic, barium, cadmium, chloride, chromium, copper, fluoride, magnesium, iron, lead, manganese, mercury, nitrate, selenium, silver, sulfate, and zinc. RO is also effective with asbestos, many taste, color and odor-producing chemicals, particulates, total dissolved solids, turbidity, and radium. When using appropriate activated carbon pre-filtering (commonly included with most RO systems), additional treatment can also be provided for such "volatile" contaminants (VOCs) as benzene, MTBE, trichloroethylene, trihalomethanes, and radon. Essentially, reverse osmosis is capable of rejecting bacteria, salts, sugars, proteins, particles, dyes, heavy metals, chlorine and
related by-products, and other contaminants that have a molecular weight of greater than 150-250 Daltons. The separation of ions with reverse osmosis is aided by charged particles. This means that dissolved ions that carry a charge, such as salts, are more likely to be rejected by the membrane than those that are not charged, such as organics. The larger the charge and the larger the particle, the more likely it will be rejected.
  
 
Arsenic
Bacteria
and
Viruses
Bad Tastes
& Odors
Chlorine
Fluoride
Hydrogen
Sulfide
Heavy
Metals
Nitrates
Radon
Sediment
Iron
YES
YES
YES
YES
YES
Approx.
YES
YES
NO
YES
YES
Yes = Effectively Removes
  1. Approx. = Significantly Reduces
No = Minimal or No Removal
* Even though reverse osmosis is effective in removing bacteria and viruses, it is not recommended that your rely upon reverse osmosis solely if your water is contaminated with bacteria or viruses. Ultraviolet (UV) purification is also recommended.
Comparison of Water Filter / Purification Technologies
There are a wide range of water filters, purifiers, and other treatment devices available on the market today. In reality, there is no single filter or treatment that will eliminate every contaminant from your water. Many technologies target only a specific type of contaminant and may be completely ineffective against others. Typically, most higher-end systems use a combination of filter technologies to achieve the best results. It is nevertheless important to choose a system that specifically targets the known or potential contaminants in your personal water supply.
Technology
Arsenic
Bacteria
and
Viruses
Bad Tastes
& Odors
Chlorine
Fluoride
Hydrogen
Sulfide
Heavy
Metals
Nitrates
Radon
Sediment
Iron
Activated Carbon
NO
NO
YES
YES
NO
Aprox.
Aprox.
NO
YES
Aprox.
NO
KDF-55*
Aprox.
NO
YES
YES
NO
YES
YES
NO
Aprox.
Aprox.
YES
Reverse Osmosis*
YES
YES
YES
YES
YES
Aprox.
YES
YES
NO
YES
YES
Ultraviolet
NO
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
Greensand Iron Filter
NO
NO
Aprox.
NO
NO
YES
Aprox.
NO
NO
Aprox.
YES
 
 
 
 
 
 
 
 
 
 
 
 
To help you gain a better understanding of each major home water filter and purification technology, we have created the following comparison chart as well as complete descriptions of the relevant technologies (select technology from list on right for details). Our products feature all of these technologies in various combinations. Compare your water testing results to the chart and information to determine your best filtration / purification options.
YES = Effectively Removes
  1. = Significantly Reduces
NO = Minimal or No Removal
 
How does industrial reverse osmosis work?

A. Industrial reverse osmosis use spiral wound membranes mounted in high pressure containers. The membrane stack is two, very long semi permeable membranes with a spacer mesh between them that is sealed along the two long sides. This is then wound up in a spiral tube with another spacer to separate the outside of the stack. The spiral winding provides a very high surface area for transfer. Between each membrane layer is a mesh separator that allows the permeate (pure) water to flow. Water is force in one end of the spiral cylinder and out the out other end. Backpressure forces the water through the membrane where it is collected in the space between the membranes. Permeate then flows around the spiral where it is collected in the center of the tube.

Q. Is any pretreatment required?

A. There are various pretreatment configurations that will work on the front of an reverse osmosis water system. Part of the selection is based on the capabilities and experience of you maintenance staff. The better preventative maintenance you have, the easier it will be to maintain a chemical addition system. Chemical metering systems require more daily maintenance and calibration to insure consistent operation. Fixed bed systems such as softeners and carbon beds require little daily maintenance.

Water must have a very low silt (solids) content to keep the membranes from plugging up. This can be accomplished by removing the solids or keeping them in suspension while passing through the system. Chemicals can be added to the incoming water to keep the solids in suspension or efficient filtration can be used. We prefer to remove all solids before the system, which results in the lowest rate of membrane plugging.

As the water passes through the reverse osmosis system, the ionic content of the reject stream increases as water permeates the membranes. This increase in TDS can results in calcium and magnesium (the hardness ions) precipitating out in the system and plugging the membranes. Again, either the Calcium and Magnesium can be removed or a chemical can be added to keep them in solution. We prefer using a water softener to remove the hardness ions and replace them with sodium.

Chlorine must be removed for thin film membranes and should be minimal for CTA membranes. Either it can be removed by carbon treatment or reduced with a chemical addition of sodium metabisulfite. The carbon is preferred because the chemical addition can enhance bacterial growth in the system which can plug the membranes.

Q. What is required to install and use a reverse osmosis system?

A. The reverse osmosis system itself is fairly simple, consisting of a series of tube containing the membranes with a high pressure pump to force the water through the system. Pretreatment is required for all systems which is designed to eliminate slit (suspended solids), water hardness and chlorine and other oxidizers. The schematic shows a simplified front end reverse osmosis system where the city water is filtered, softened to remove hardness, the carbon is used to remove the city chlorination (membranes are sensitive to oxidizers). An alternative would be to dose the system with chemicals to remove the chlorine and hold the hardness ions in solution.

After the carbon filter, the water is passed through the membranes where the concentrate is recycled back to the front of the system for another pass and a bleed is taken off this line to drain. This recycling allows very high system efficiencies.

The permeate line will have a TDS (total dissolved solids) level of about 4% or less of the incoming water (membrane dependent). A sidestream off this line feed a DI bottle service for DI water. The TDS is only 4% of the incoming water so the DI bottles will last 25 times longer!

Q. How much pressure is required to purify water?

A. The pressure required is dependent on the concentration of the salt solution on the reject (concentrate) side of the membrane. Running as system at 1100 PPM on the concentrate side requires over 200 PSI. Sea water systems at 33,000+ PPM run at 800+ PSI. Under sink systems at home run at 50-70 PSI.

Q. How pure will the water be?

A. Purity is determined by two things, first the "reject ratio of the membrane (92-99.5%) and secondly, the type of salts in solution. Membranes are very good at rejection high molecular weight compounds and multivalent ions. Monovalent ions such as Na+ and Cl- (Sodium and Chloride) are not rejected as well and are the leakage ions. The amount of leakage is determined by the reject ration. A 95% reject ration means that 5% of the salt concentration leaks through so a 200 PPM input stream would result in a 10 PPM output stream. A membrane rated at 99% would result in a 2 ppm output stream. The reject ratio changes over the life of the membrane and leakage increases. Each time you clean a membrane it slightly changes its properties so after many years the ratio may drop to 90% or less.

Q. What about membrane plugging?

A. As you concentrate salts on one side of the membrane, you can reach a point where salts of the hardness ions (or other ions) precipitate out. When they do, this will plug the very small pores of the membrane. Organic compounds can also plug the pores. Once plugged, the flow decreases and the membrane must be cleaned. Hardness can be eliminated by softening or continuously dosing a chemical chelating agent.

Q. How can I prevent plugging?

A. Initially the incoming water if filtered to remove particulates and colloidal substances. After this there are two ways to reduce the chance of plugging. A chemical can be added to the feed stream that keeps the hardness from precipitating out. This is simply metered directly into the pipe feeding the reverse osmosis pump. The second way is to remove the hardness with a water softener. This will reduce the chance of plugging and also acts as another filter in front of the system.

Q. How do I clean a system?

A. Cleaning is fairly simple. A volume of water is recirculated on the high pressure side of the system with a cleaning agent (for hardness or organic plugging) for an hour or so then the membrane is flushed to drain and returned to service.

Q. How much maintenance is involved with a system?

A. If properly setup with effective pretreatment, a system usually has a 1 hour cleaning cycle once per month or even less often when softening is used as a pretreatment. A softener needs a daily check of salt level. Prefilters need a weekly check. Usually filters are alarmed through flow rate so absolute monitoring is not necessary.

Q. How much floor space does a reverse osmosis system occupy?

A. Integrated systems up to 50 gpm can occupy a space of 6 feet by 15 feet by 6 feet high without storage tanks. A 30 minute holding tank after the system is usual and if recycling is used, a 10 minute storage tank to feed the reverse osmosis pump is used.

Q. How much does it cost to run a reverse osmosis system?

A. The cost to operate is a total of three variables. These are, power, chemistry (pretreatment and pH adjust) and labor.
Power Costs-

The power requirement is about 10 hp for 30 gpm up to 15 hp for 60 gpm. This is constant while the system is running. A 10 hp, 3-phase motor costs about 15 cents per hour to operate (or less).
Chemistry Costs-

The chemistry costs for pretreatment involve either salt for a water softener or a polymer or sequestering agent to keep the hardness ions from precipitating out. A pH adjustment is also usual with citric acid. Total costs for a 30 gpm system runs about 10-15 dollars a day.
Labor costs-

Labor costs for the system is usually very low due to the automated nature of the systems. If the proper pretreatment is used, little or no maintenance is required between cleanings except for chemical maintenance for the pH adjust system and softener or polymer systems. Calibration of pH probes is a weekly project. Cleaning is a simple chemical recirculation procedure taking about 1 hour.

Q. How much water is rejected?

A. This will vary with the configuration of the system. Up to 6 membranes can be connected in series and the theoretical capture rate is about 84% (rejecting 16%). We have use oversized systems and redirected the reject to the front of the system for a multiple pass system and have gotten recovery's of about 92% (half or the reject to drain, half to the system feed tank). This does require oversizing the pumps and system size to get the required flow rate.

Q. How do I dispose of reject water?

A. Reject water is discharged directly to drain. Usually the TDS is less than 1500 PPM and there are no contaminants. If a system is used to recycle some water after a plating application, monitoring of the reject may be necessary.

Q. What types of membranes are there?

A. There are two types of membrane materials in widespread use. These are thin film (TF) and Cellulose Triacetate (CTA) membranes. The thin film membrane is chlorine sensitive and requires carbon pretreatment to remove the chlorine. The CTA membranes don't. TF membranes have a little higher reject ratio and operate at a wider pH range than the CTA.

Q. Do I have to shut down for cleaning?

A. Small systems will have to shut down but in larger (>10 gpm) systems, the individual banks of membranes can be isolated and cleaned one at a time and only part of the flow will be lost.

Q. Do I have to pH adjust before the reverse osmosis system?

A. Complete systems have a pH adjust module to reduce the pH to between 5.5 and 6.5. This helps to prevent plugging of the membranes and aids in cleaning the system. If the system is to be used in water recycling, pH adjust is mandatory.

Q. What about bugs (bacteria) growing in the water?

A. RO systems are sterilized periodically during cleaning. The water storage from a reverse osmosis system is optionally passed through an UV sterilization system, which kills any bacteria in the system. All tanks should be black or opaque to prevent algae growth.

Q. How automatic is automatic?

A. Our standard systems have PLC controls with alarms and full sensors compliments. Full automatic controls are available including data monitoring, storage and analysis as are network interfaces. A typical system will have a holding tank with level controls feeding the reverse osmosis pump and a reverse osmosis water storage tank with level controls and duplex pumps for shop water pressurization. All this is monitored and controlled by the PLC. Gages and instrumentation include high pressure gages on the reverse osmosis pump output and concentrate output, pressure switches on the reverse osmosis feed and output (monitored by the PLC), and flow monitors (sight gages on smaller systems, electronic on larger ones) on the concentrate, permeate and recycle stream. Even the cleaning cycle can be automated on larger systems with automatic valves to isolate selected banks so down time is minimized.

Q. How long will my reverse osmosis membranes last?

A. Reverse osmosis membranes usually last many years. They rarely fail all at once. Usually they slowly start leaking more ions until some unacceptable level is reached. There are membrane systems that have been in continuous use for 20 years. It is much more cost effective in the long run to buy over capacity initially so you can get several years more useful life out of the membranes.
RECYCLING WITH REVERSE OSMOSIS
Q. Can I use an reverse osmosis to recycle water?

A. Maybe. Reverse osmosis systems are very sensitive to plugging so the recycled stream must be carefully evaluated as to ionic and particulate content. Effluent water from a MRIX system can be recycled (see drawing). Water directly from a scrubbing system probably shouldn't be recycled without proper pretreatment.

Q. Should I evaporate to concentrate the reject? The Zero Discharge option!

A. Evaporation is an expensive way to concentrate solutions unless there is a lot of waste heat available. Evaporating 3+ gallons per minute is very expensive, both to purchase the equipment and to operate the system. Evaporation is the only practical way to get to zero discharge, but the cost is high.

Q. What does a carbon filter do?

A. Carbon is derived from either wood or coal (or coconut shell!). The starting material is heated in an inert atmosphere to convert it to pure carbon. The way it is processed results in a very high surface area and an ability to adsorb various material. The capacity for both organic and inorganic materials is high but carbon is usually used for adsorbing organics. Each organic and each type of carbon have a different adsorption capacity.

Carbon is used to adsorb organics, chromates, sulfides and chlorine. It is used to prevent strong oxidizing materials, such as peroxides, nitric acid, and chlorine, from attacking membranes and it is used as a general adsorbent in recycling systems.

Q. How would an reverse osmosis be used to recycle water?

A. The following schematic shows a recycling schematic as would be used at a plating shop. Some of the details are left off to increase the clarity of the drawing. There are actually two different systems integrated into one to obtain the best cost/benefit ratio. Inside the dashed line is a complete Metal Recover Ion Exchange (MRIX) system to remove target metals from the waste water. Instead of the MRIX system, a microfiltration unit or a clarifier with very good final filtration could be used. After the MRIX the water has been filter and is carbon treated to remove any residual oxidizers or organics.

The second system is a complete front end reverse osmosis system with reverse osmosis feed water storage and pH adjust and full city water pretreatment. The MRIX effluent water is injected into the reverse osmosis feed tank where pH is adjusted. This water can be diverted to drain by the PLC during regenerations when the TDS is very high. An shortfall in water is made up with city water. A low level at the reverse osmosis feed tank fills it with softened/carbon treated city water.

The percentage recycled by such a system depends on how much of the reverse osmosis systems output is sent to rinses returned to the MRIX system. If you are feeding rinses that bypass the MRIX, the percent of recycled water will be low. If all goes to the MRIX, the ratio can be 80-90 percent.
 
By applying a pressure that exceeds the osmotic pressure, the reverse effect occurs. Fluids are pressed back through the membrane, while dissolved solids stay behind.

To purify water by Reverse Osmosis membrane, the natural osmosis effect must be reversed. In order to force the water of the brine stream (high salt concentration) to flow towards the fresh stream (low salt concentration), the water must be pressurized at an operating pressure greater than the osmotic pressure. As a result, the brine side will get more concentrated.
The operating pressure of seawater is around 60 bar.
 
1. Water flows from a column with a low dissolved solids content to a column with a high dissolved solids content

2. Osmotic pressure is the pressure that is used to stop the water from flowing through the membrane, in order to create balance

3. By pursuing pressure that exceeds the osmotic pressure, the water flow will be reversed; water flows from the column with a high dissolved solids content to the column with a low dissolved solids content

Small Reverse Osmosis Plant
 
*Low energy or high rejection membranes
*All equipment mounted on stainless steel 304 skid
*Available in complete Stainless Steel piping
*Standard control with RO micro-controller and conductivity display
*Advanced control with flow, pressure, pH and conductivity transmitters for data monitoring, normalisation and SCADA.
*The system includes:
*5 microns filter
*High pressure pump
*RO or NF 4 " membranes
*Fiber glass pressure vessels
*Standard or advanced instrumentation
*Option: antiscalant dosing station
 
 
Type BWRO S
250
500
750
1000
1500
Permeate flow * l/h
250
500
750
1000
1500
Feed flow l/h (80% recovery)
315
625
940
1250
1875
Rejection
>96% Reverse Osmosis, 80% Nanofiltration
Connections
 
 
 
Feed
DN 25, PVC glue
Permeate
DN 20, PVC glue
Concentrate
DN 20, PVC glue
Power 400V, 50Hz**
1.5 kW
2.2 kW
2.2 kW
2.2 kW
3.0 kW
Dimensions (mm)
 
 
 
 
 
Length
1100
1800
450
Width
Height
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  * under standard conditions: TDS< 1500ppm, temperature = 12oC, pH = 7.5
** Also available in 110V, 60 Hz
* under standard conditions: TDS< 1500ppm, temperature = 25oC, pH = 7.5
** Also available in 60 Hz
These data are given for information purpose only. They are subject to modifications depending on the water quality.

Reverse Osmosis or Nanofiltration units often required pre-treatment for the following parameters:
- Suspended solids
- TOC, COD/BOD, hydrocarbons
- Iron and manganese
- Hardness
Lenntech provides all kinds of pre-treatment required before your RO, like multimedia filters, water softeners or de-ironing filters, according to your water analysis and process requirements.

General design data for Reverse Osmosis Plants:
 
TWRO
Tap water
BWRO
Brackish water
SWRO
Sea water
Salinity
< 1500 ppm
< 8000 ppm
35000 - 45000 ppm
Recovery
80%
65-80%
35-45%
Working pressure
< 15 bar
15-25 bar
50-75 bar
Membrane types
Tap/Brackish 4" or 8"
Seawater 4" or 8"
Flux
30-35 l/h.m2
25-30 l/h.m2
15-20 l/h.m2
Specific energy at 25 oC
< 0.75 kWh/m3
1.5 kWh/m3
5 kWh/m3 or 2-3 kWh/m3 with energy recovery
Configuration
Skid mounted or containerized (10 to 40 ft)

RO Membrane Cleaning
 
Reverse Osmosis membranes and other membrane systems need periodic cleaning and servicing. For optimal performance specific chemicals are required, depending on the cause of the pollution.
Scaling
Scaling is concerned with the seclusion of suspended inorganic particles, such as calcium carbonate, barium sulfate and iron compounds.

Fouling
Fouling is concerned with the seclusion of organic, colloidal and suspended particles. Bacteria and other microorganisms that decompose these particles will create substrates. As a consequence they will grow and develop further.
The processes that are mentioned above will cause a decrease in capacity and/or an increase of the pressure and, as a result, of the energy use.
It is very important to purify the membrane preventively. In many cases regular mild cleaning is better than cleaning periodically with an aggressive cleaning product. The membrane will than last longer.
Calcium carbonate scaling
Mainly occuring in hard water
Use our anti-scalant
Biofilm formation
Growth of micro organisms on the membrane
Apply our disinfectant
Iron deposits
Removal of iron containing deposits
Treat with our removal chemical
Organic deposits
Oil and organic deposits
Efficient treatment with our cleaning aid
 
 
Frequently Asked Questions About Reverse
Osmosis
1. What is Reverse Osmosis?
Reverse osmosis, also known as hyper filtration, is the finest filtration available today. It is the most common treatment technology used by premium bottled water companies.
2. How does Reverse Osmosis work?
Reverse osmosis uses a membrane that is semi-permeable, allowing pure water to pass through it, while rejecting the contaminants that are too large to pass through the tiny pores in the membrane.
3. Can Reverse Osmosis be used on well water or water from other untreated sources (lake or river)?
Yes, RO is generally an excellent choice for homeowners with well water. However, it is important to note that reverse osmosis does not provide foolproof protection against all microorganisms. You should have your water tested for bacteria, virus, and cyst contamination before relying solely on reverse osmosis. If microbiological contamination is present or suspected, you should combine reverse osmosis with an ultraviolet system for maximum effectiveness and protection against bacteria and viruses. A water softener or whole-house iron filter may also be advisable (depending one the level of relevant contaminants in your well water) to prevent membrane fouling thereby ensuring maximum membrane life and effectiveness.
4. How often does the reverse osmosis membrane need to be replaced?
With proper maintenance of your sediment and activated carbon pre-filters, your reverse osmosis membrane should last 2-3 years.
5. Why are reverse osmosis systems always combined with carbon and sediment pre-filters?
The only major category of contaminants that reverse osmosis is not highly effective in removing (organic compounds) is specifically targeted by activated carbon filters. Pre-filters also prevent the reverse osmosis membrane from being fouled or clogged by sediment, chlorine, and other contaminants, thereby enhancing its effectiveness and lifespan.
6. Are all reverse osmosis systems equally effective?
Absolutely not. Like all water filters, the effectiveness of a reverse osmosis system depends greatly on the quality of its components - especially its pre-filter cartridges and the membrane itself. Lower quality pre-filters will suffer from premature membrane fouling, as well as reduced performance, purified water output, and membrane life. TFC membranes are also much more effective than CTA membranes.
7. I notice that a reverse osmosis system will remove just about everything from my water, including some nutrients that are good for the body. Should I take a supplement to counteract the nutrients that I will no longer get through my water.
No, this is not necessary. You should already be getting all of the nutrients such as essential salts, vitamins, and other trace minerals from the food you eat and the other beverages you drink.
8. What is "cross flow"?
Quality reverse osmosis systems use a process known as cross flow to allow the membrane to continually clean itself. As some of the fluid passes through the membrane the rest continues downstream, sweeping the rejected contaminants away from the membrane and down the drain. This prevents contaminants from backing up against the membrane and clogging it.
9. How much filtered water can a home RO system produce?
Our RO systems produce up to 50 gallons of purified water per day but can be upgraded to 100 gallons per day if desired (at extra cost). If you opt to upgrade your membrane, you may need to also upgrade the storage tank to gain the benefit of the larger membrane. The actual amount of water produced in your home will depend on your household water pressure. Because reverse osmosis water purification occurs slowly (it is a very fine filter!), a storage tank is used to hold 3 gallons of purified water at all times so pure water is always at your finger tips.