Understand the reverse osmosis water filter
Reverse osmosis water filter principle
Before we understand how a reverse osmosis water filter works, we have to understand how normal osmosis works. In a normal osmosis process, the solvent moves through a semipermeable membrane from a low solute concentration side of the semipermeable membrane to a higher solute concentration on the other side of the semipermeable membrane.The semipermeable membrane allows water to pass through but not ions or larger molecules. The movement of the solvent is due to osmotic pressure. The osmosis process will stop when and equilibrium of the osmotic pressure is achieved on both side of the semipermeable membrane.
The principle behind reverse osmosis water filter
In reverse osmosis, the opposite of the process happens. An external pressure is applied to the high solute concentration side of the semipermeable membrane which forces the solvent to move to the other side of lower concentration. The pressure applied reverse the osmotic process. The membrane acts like a very fine filter to produce a drinkable water from an unclean or salty water.
Components in reverse osmosis water filter
Reverse osmosis water filter is developed based on this principle to produce clean and pure drinking water for household. A typical reverse osmosis water filter normally would have a residue filter to filter out unwanted particles such as rust or calcium carbonate, an activated carbon filter to get rid of chlorine and organic chemicals and a reverse osmosis filter which is a film of thin composite membrane. Optionally, some would have a second sediment filter with smaller pores to give trap those particles that escape the first filter. Some would have an additional extra carbon filter to trap any chemicals not filtered by the membrane. More advance reverse osmosis water filter would include an ultra-violet lamp to disinfect any microbes that may escape the reverse osmosis membrane filtering. All these are usually housed in a casing with a storage tank and a faucet to deliver the filtered water for your consumption.
Reverse osmosis water filter membrane
There are two types of membrane commonly used in home reverse osmosis water filter – Cellulose Triacetate (CTA) and Thin Film Composite (TFC). TFC membranes are more efficient in filtering out contaminants compared to CTA membrane. But the minus point is that it is easily subject to degradation by chlorine. That is why it is important that a reverse osmosis water filter must have quality activated carbon pre-filters to protect the membrane.
The end results
Reverse osmosis water filter is a good choice for most homes because it is able to remove most inorganic chemicals and most microorganisms.
How does reverse osmosis water filter works?
Reverse osmosis water filter works
Reverse osmosis water filter works by forcing the water to pass through the membrane and the unwanted substances are flushed out using the unprocessed water and diverted to the drain. In other words, the water are forced through a 0.0001 micron semi-permeable membrane by applying high pressure. The membranes are usually a long sheets of membrane rolled up around a hollow tube in a spiral way. This is referred to as a spiral membrane or also called a module. The size of the module is normally about 2 inches in diameter and about 10 inches in length.
The membrane is normally housed in a membrane housing or a container. And when pressure is applied, the water are forced through the membrane filtering out any unwanted substances. The unwanted substances are then diverted and flushed out of the reverse osmosis water filter. This will prevent any unwanted substances from accumulating in the filter and clog up the membrane which will compromise the quality of the filtered water. This is the advantage of this water filter compared to other conventional water filters. This is also the reason why reverse osmosis water filter can last longer and function well with minimum maintenance.
All reverse osmosis water filters work the same way and may look alike to some extend. They usually have the same basic components. The main difference is the quality of the membrane used and this will determine the quality of the filtered water. Reverse osmosis water filter usually has carbon pre-filters to filter out chlorine to protect the membrane as membrane in the reverse osmosis water filter can be damaged by chlorine.
The basic process of a reverse osmosis water filter is as follow:
Reverse osmosis water filter pre-filtration
This first step of water purification process is where large particles and unwanted substances or impurities are removed from the water. The pre-filter is a carbon filter or activated carbon-based filter to protect the semi-permeable membrane and need to be changed regularly to keep the filter in good condition.
Reverse osmosis water filter membrane
This is the second stage in the water purification process of reverse osmosis water filter. The semi-permeable membrane will remove all impurities in the water that has passed through the pre-filter. The semi-permeable membrane is so fine that high pressure has to be applied for the purified water to pass through. The contaminants that was trapped will be flushed out as waste water.
Reverse osmosis water filter water tank
There is water holding tank to store purified water for consumption. The tank is needed to store a few gallons of purified water ready for consumption. The reverse osmosis process is slow and is not able to keep up with the demand. That is why reverse osmosis water filter has to have the water storage tank.
Facts to consider when choosing a reverse osmosis water filter.
Reverse osmosis water filter facts to consider
Reverse osmosis water filter is the most preferred water filter in most household. It can remove contaminants effectively compared to most water filters available in the market.
There are many different types of reverse osmosis water filter available for you to choose from. Considering that you will be drinking the water that comes out from the filter, you may want to find the best reverse osmosis water filter to give you the peace of mind knowing that the water that comes out from the filter in your home is safe and free from all contaminants. Different filter has different quality. So make sure that when you shop for one, check the quality of the material used and the warranty that comes with it.
Replacement filter for reverse osmosis water filter
Beside the quality of the materials used, ensure that the replacement filter is easy to change so that you can do the change yourself. This will help to save lots of money in the long run. The life span of the filter should be ideally around 12 months. If possible, the size of the filter should not be a customised for a particular brand of reverse osmosis water filter. Choose one where the size is standard and compatible with other brands in the market so that you would not have to stick to one brand of replacement parts only. This will save you a lot of trouble if the supplier of that particular brand folded their business or decided to increase their prices tremendously.
Quality of reverse osmosis water filter
Cheap water filter may not have the quality expected of it. They may be made of sub-standard materials which may crack under pressure over a period of time. But be aware that there are some with high price tags but of low quality as well. So check the reputation of the supplier before committing yourself to a particular brand. Do not entertain suppliers who do not disclose all the information about the parts or hold back certain information about the filter.
Pre-filter for reverse osmosis water filter
Ensure that the reverse osmosis water filter has carbon pre-filter to protect the membrane from chlorine. Chlorine can damage the membrane and the quality and purity of the filtered water depends very much on the quality and condition of the membrane. So it is utmost important to protect the membrane properly.
Reverse osmosis water filter supplier
Choose to buy from an established supplier with good customer service and efficient technical support team. You will be using the reverse osmosis water filter for a long time and you want to ensure that they are there to give you the support when needed.
Is reverse osmosis water filter the right water filter for me?
Reverse osmosis water filter pros and cons
Reverse osmosis water filter works well for every household water purification needs as it is able to filter bacteria and virus effectively. But it is only recommended for homes using pre-treated municipal water. It is not suitable to be used for water from the lake or well water. For instances such as these, it is highly recommended to add the use of ultraviolet light at the end of the filtration stage to ensure that any bacteria or virus that escape the filtering process is eliminated.
Water softener can also be used in advance of the reverse osmosis water filter if the water is extremely hard to prevent the membrane and pre-filter from being damaged.
Reverse osmosis water filter is highly recommended in agricultural areas where water is highly contaminated with nitrite.
The advantages of reverse osmosis water filter.
1. It can remove a wide range of contaminants in comparison to other common water filters.
2. It produces pure and clean drinking water for your home.
3. It is very cost effective in the long run after taking into account the cost of water and maintenance.
4. Easy to maintain as you can change the replacement parts easily.
5. This filter delivers quality water directly from the faucet of your home and thus eliminates the use of water bottles and are more environmental friendly.
The disadvantages of reverse osmosis water filter.
1. Requires the carbon pre-filter to protect the semi-permeable membrane which is easily damaged by chlorine.
2. For each gallon of pure water processed, it produces 3 to 6 gallons of waste water . The waste water is necessary to clear the unwanted particles from the filter to prevent any clog up. The waste water can be re-captured to be used in the toilet or for any other purposes other than drinking.
3. It removes all natural minerals in the water. These minerals are vital to our body. Water without minerals are not healthy for the body. But fortunately, we can get these minerals from other sources beside water. Only a small percentage of the minerals we need comes from the water.
4. Reverse osmosis water filter is generally slower in its process compared to other conventional water filters.
Reverse osmosis water filter conclusion.
All water filters have their own advantages and disadvantages . Reverse osmosis water filter produces pure and clean drinking water as it is able to remove most contaminants. Reverse osmosis water filter is the preferred water filter in many household.
Reverse osmosis water filter semi-permeable membrane
Reverse osmosis water filter maintenance
The semi-permeable membrane used in the reverse osmosis water filter system consist of a few thin layer or sheets of film that are rolled in a spiral form around a plastic tube. The semi-permeable membrane allows water molecules to pass through but not contaminants. The water molecules pass through the membrane and will be collected in the centre tube. The contaminants which are trapped on the surface of the membrane are then washed off the surface of the membrane to avoid clogging which can affect the effectiveness of the filter.
Reverse osmosis water filter cleaning.
After a period of usage, the effectiveness of the membrane to filter the water reduces. The residue of salts and minerals on the membrane over the long term may result in reduced water production. The concentrated salts and minerals on the membrane surface will plug the small and tiny pores of the membrane. The water flow will decrease and the membrane must be cleaned. To prevent plugging, a chemical can be used and added to the water feed stream or a water softener can be used to remove the hardness of the water. Cleaning the membrane is quite simple. A large volume of water is recirculated on the high pressure side of the reverse osmosis water filter with a cleaning agent for about an hour or so. Then it is flushed to clear whatever unwanted particles and the filter is ready for use again.
Reverse osmosis water filter monitoring.
Proper setup with good pretreatment, the reverse osmosis water filter needs only 1 hour cleaning cycle per month. Pre-filters may need to be checked once a week. Close monitoring may not be necessary as the flow of water will give you an indication of the condition of the reverse osmosis water filter.
Reverse osmosis water filter semi-permeable membrane life cycle.
The quality of the water produced may be compromised when the membrane has reached the end of its life cycle. You may notice some white sediments at the bottom of your kettle and the water have a different taste. This may mean that the membrane is disintegrating and needs to be replaced. Reverse osmosis water filter membranes usually last many years. They don’t normally failed all at the same time. They will start leaking ions and that is a telling sign that the membrane in the reverse osmosis water filter is failing.
The myths around reverse osmosis water filter.
Reverse osmosis water filter myths
There are many myths that claim that reverse osmosis water filter produce pure water that is too pure and not healthy for human consumption. We listed down some of the more common myths around and we also noted some explanation to help you decide whether the myths are true.
Myth: Purified water from reverse osmosis water filter is not good for health.
People said that reverse osmosis water produced by reverse osmosis water filter is unnatural because it is too pure and that it is man-made and not suitable for our human body. It is meant only for industrial use. Reverse osmosis water does not exist in this world.
The truth is this type of pure water does exist. And it is rain water. Rain water has no minerals and it is the purest and cleanest water in this world. Since the creation of this world, people have been drinking rain water for years and they experience no side effects or ill health. Only because the world is polluted now that rain water is no more clean and not suitable for drinking purposes. Rain water is the best water that our mother nature can produce. Rain water has no minerals as well. Thus people have been drinking water without minerals for years and that is all normal.
Scientific research done on reverse osmosis produced by reverse osmosis water filter over the years has shown no negative effects on human health. Reverse osmosis water filter has been used to produce reverse osmosis water for the US military and it is highly approved.
Myth: Reverse osmosis water filter removes healthy minerals from the water.
The truth is reverse osmosis water filter removes inorganic minerals which is not good for human body. Reverse osmosis water filter does remove minerals from the tap water. No doubt it is true but our human body gets a large amount of the minerals that we need from the food we eat. And not from drinking water. Inorganic minerals are hard for our body usage and cannot be absorbed properly by our body. We need organic minerals which can be obtained from plants which can be easily absorbed by our body. Water Quality Association (WQA) and World Health Organisation (WHO) has mentioned that we get most of our minerals from food and not water. Inorganic minerals in water is not good for our health.
Myth: Reverse osmosis water filter produces water that leaches minerals from our body.
Water is known as the universal solvent and tend to disolve substances in it. It has the pulling force to disolve substances. The purer the water the more power it has to disolve things. This leads to the myth to say that reverse osmosis water because of its pure form, tends to leach minerals from our body. But the truth is, our physiology quickly achieves homeostasis using stomach juice, saliva etc to achieve equilibrium of all our bodily fluids. Thus reverse osmosis water from the reverse osmosis water filter will not leach minerals from our body.
Myth: Reverse osmosis water filter produces acidic water
Reverse osmosis water filter may or may not produce low pH water as it removes unhealthy inorganic minerals from the water. Water pH levels vary depending on many factors. But the truth is, water pH automatically change when it reaches the stomach and mixed with food. The human body adjust pH levels to reach an equilibrium and to maintain a pH at 7.4. Even eating acidic food will only adjust the body pH by a small level and for a short time. Soft drinks, coffee and orange juice has low pH and we drink these almost everyday without any problems. It is safe to drink water from reverse osmosis water filter even if the pH is low and acidic.
Reverse osmosis water filter and hard water.
Reverse osmosis water filter water softener
Does reverse osmosis water filter need water softener? The answer depends very much on the condition of the water supplied to your household. Water softener is a separate system and is independent of reverse osmosis water filter. If the water is hard water, then it is recommended to use water softener. Hard water has high content of minerals. It contains high concentration of calcium and magnesium ions. Groundwater usually has higher contents of these minerals as they absorbed them by dissolving them from the rocks and soil in the area. Hard water does not cause harm to health but may cause problems in equipments that handle water in domestic or industrial setting as it can cause building up of limescale in pipes and tanks. The built up of calcium and magnesium in reverse osmosis water filter can cause clogging of the semi-permeable membrane. Beside clogging up the reverse osmosis water filter semi-permeable membrane, it can also make soap lose its effectiveness.
Reverse osmosis water filter and well water.
Reverse osmosis water filter is recommended for homes using municipal pre-treated water which is usually not as hard as well water. Reverse osmosis water filter is not recommended for homes using well water or water sourced from lake or river unless it is combined with ultraviolet for complete protection against bacterias and viruses. Ultraviolet is able to destroy bacterias and viruses effectively to make the water safe for drinking. Well water is usually harder too. Hard water can reduce the efficiency of reverse osmosis water filter in the long run. Water softener can be used in advance of the reverse osmosis water filter to prevent any breakdown of the pre-filter or semi-permeable membrane and to prolong its life span.
Reverse osmosis water filter – water softener
Conventional water-softening used in household very much depends on ion-exchange resin. It changes the hardness ions with sodium ions to make the water soft. A water softener has two tanks. One tank contains resin and the other contains salt water. The resins which are negatively charged are bonded with the sodium ions which are positively charged. The water flows through the tank containing the resins and the calcium and magnesium ions in the water which are more positively charged are exchanged with sodium ions from the resin. The removal of calcium and magnesium turns hard water into soft water. Soft water will be more gentle to the reverse osmosis water filter.
What reverse osmosis water filter is and what it is not.
Reverse osmosis water filter facts
Reverse osmosis water filter was developed based on water purification method developed by US navy to produce drinking water from sea water for it submarine crews. The sea water was forced through the semi-permeable membrane by using pressure. This resulted in purified drinking water and all contaminants and salt was removed. The reverse osmosis method was adapted for home by combining carbon filters and ultraviolet into reverse osmosis water filter to produce pure and clean water for household consumption.
Reverse osmosis water filter vs distiller.
Reverse osmosis water filter is not like a distiller. Both methods remove contaminants from the water but the processes differ. Reverse osmosis water filter uses a semi-permeable membrane to remove the contaminants. Distiller removes the contaminants by boiling the water, collecting the steam, condense it and harvest the purified water. Distiller removes most contaminants but is not effective when it comes to chemicals with low boiling points such as Chloramine which are used instead of chlorine to treat water. Chloramine are not completely removed by distiller. They will be released into the air in the confined area and will end up in the distilled water. But in general, both distilled and reverse osmosis water are pure and clean.
Reverse osmosis water filter and chlorine.
It is true that reverse osmosis does not remove the chlorine in the water. But this is taken care of by the carbon pre-filter in the reverse osmosis water filter. The pre-filter will remove the chlorine to protect the semi-permeable membrane. And it is true too that reverse osmosis removes all the minerals in the water. But the minerals in the water are inorganic and hard for our body usage. Our body can obtain the minerals it needs from food. The main concern in water is not the minerals that have been removed but the chemicals that it contains. Reverse osmosis is capable of removing all the harmful chemicals.
Reverse osmosis water filter and high water usage.
There are arguments that say that reverse osmosis water filter waste a lot of water. Unwanted particles and contaminants are removed out of the reverse osmosis water filter using the waste water. For each gallon of pure water it processed, there will be 3 to 6 gallons of waste water produced. It may look like a lot of waste water but do you realise that you use almost similar amount of water for washing cars, flushing toilets, washing dishes or clothes? A reverse osmosis water filter uses water but it will not make a whole lot of difference in your water bill.
Introduction to types of reverse osmosis water filter.
Reverse Osmosis Water Filter Types
Reverse osmosis water filter works by forcing water or solvent through a semi-permeable membrane and filter out the contaminants which was then drain out of the system. The reverse osmosis water filter system would normally have sediment filters both before and after the semi-permeable membrane. The pre-filters would filter out the chlorine to protect the semi-permeable membrane which is sensitive to chlorine.
There are many types of reverse osmosis water filter available in the market for you to choose from depending on your requirements.
Under counter residential reverse osmosis water filter.
Like what have been describe above, under counter reverse osmosis water filter system filters the water in several stages. It has the pre-filtration phase where chlorine are removed from the water to protect the semi-permeable membrane and at the same time, any small particles or suspended materials are filtered out. The water are then force to pass the semi-permeable membrane to remove any contaminants. There is usually a water storage tank to store the processed water and another carbon post-filter to remove any odour or taste. This water filter is able to handle water pressure ranging from 40 and 100 psig and produce up to 75 gallons per day.
Counter top reverse osmosis water filter.
Counter top reverse osmosis water filter provides a better alternative if a permanent installation is not feasible or when there is not enough space for an under counter unit. It is easily installed by connecting to any standard faucet and quite mobile. It is usually smaller in size compared to the under counter system. It normally has the same filtration pre-filter, semi-permeable membrane and post-filter as the under counter system. But instead of pressurized water storage tank, it uses an atmospheric compared to the pressurized storage tank.
Commercial reverse osmosis water filter.
Commercial reverse osmosis water filter operates on a higher water pressure between 100 psig to 220 psig. This commercial water filter system is used where large volume of water are treated and high level of purity is expected. The filtration process are the same as the residential water filter system but commercial system is more complicated and more expensive as more components are needed such as pumps, electrical supplies and others. Due to the larger built, it is usually installed mounted to the wall, floor or framed mounted.
Whichever type of reverse osmosis water filter you choose, you can be rest assured that you are getting the best clean and pure drinking water for your home.
Basic components common to all reverse osmosis water filter
- Reverse osmosis water filter parts
Reverse osmosis water filter comes in all shapes and brands but the basic components are more or less similar for all the different makes.
Reverse osmosis water filter water inlet valve
This is the valve that connects the reverse osmosis water filter to the water supply line that supplies water to your home. The valve is connected to the water inlet by a tube. This is the water source that supplies water to be processed by the filter.
Reverse osmosis water filter pre-filters
These pre-filters are fixed before the water filter so that water from the supply line pass through the pre-filters to remove all unwanted particles , sediments and chlorine. There maybe more than one pre-filter used depending on the brand of reverse osmosis water filter. Normally carbon pre-filters are used to remove chlorine which may harm the semi-permeable membrane. Pre-filters are used to protect the semi-permeable membrane beside filtering out silk, dirts and other sediment.
Reverse osmosis water filter membrane
This is the main part of the water filter system. The semi-permeable membrane will remove all impurities by applying pressure to the water to force it through the tiny pores of the membrane which is usually around 0.0001micron. There are two types of membrane which are normally used. Cellulose Triacetate (CTA) is tolerant to chlorine and Thin Film Composite (TFC) which is not tolerant ot chlorine. If TFC is used, a carbon pre-filter is necessary to protect the membrane from chlorine.
Reverse osmosis water filter storage tank
Processed water are stored in a storage tank which can hold up to 2.5 gallons of water. There is a bladder to keep the pressure in the water tank when the tank is full.
Reverse osmosis water filter post filter
Carbon or activated carbon post filter is used as to filter the purified water that comes from the storage tank. This post filter will remove any odour or taste from the water before leaving the water filter to the faucet.
Reverse osmosis water filter automatic shut off valve.
This shut off valve will stop the water from entering the membrane when the storage tank is full and stops the filtering process. The outflow of waste water also stops. When purified water is drawn from the storage tank, the pressure in the tank reduces and the valve opens to allow the purifying process to begin and waste water being released to the drain.
Reverse osmosis water filter check valve.
This check valve is fixed at the outlet of the water filter membrane housing. This valve will prevent any backward flow of purified water from the storage tank to the membrane. Backward flow would damage the membrane.
Reverse osmosis water filter flow restrictor
This flow restrictor regulates the flow of water through the membrane to produce the highest quality of purified water. Without this device located at the drain line tube, very little purified water will be produced as water from the supply line will simply flow down the drain line where there is less resistance.
Reverse osmosis water filter faucet.
The water filter has its own faucet installed at the kitchen sink where drinking water can be drawn.
Reverse osmosis water filter drain line.
This drain line is connected to the outlet of the water filter membrane housing. This line allows the waste water which contains all impurities and contaminants which was remove from the tap water during the purifying process.
The above components listed are common to all reverse osmosis water filter.
