Ensuring the purity of drinking water in the home is a matter of utmost importance for the health of the entire family. Reverse osmosis systems have proven themselves to be one of the most effective solutions for deep purification of liquids from impurities, hardness salts and bacteria. However, even the most advanced equipment requires regular maintenance to maintain high performance.
Timely replacement of cartridges is not just a formality, but a necessity dictated by the physics of the filtration process. Over time, the pores of the membrane and prefilters become clogged, the resource of the sorbents is depleted, and the quality of the outlet water begins to steadily decline. In this article we will look in detail at how to change a reverse osmosis filter without calling a technician.
The replacement process is quite simple and does not require specialized tools if you know the basic nuances of the design of your device. We will look at the stages of preparation, the algorithm of actions for different types of flasks and answer questions that owners of water purification systems often have.
When is it necessary to change cartridges in the cleaning system?
The first sign that the life of the filter elements is coming to an end is a change in the volume of the storage tank. If previously the tank was filled in 40-50 minutes, but now this process takes one and a half to two hours, it means that the throughput of the membrane has dropped. This may be due to contamination of the prefilters or depletion of the resource of the reverse osmosis membrane itself.
The second important indicator is the taste and smell of water. Activated carbon, used in post-filters and pre-filters, has a strictly limited resource. When it runs out, the water may taste like chlorine, have a foreign odor, or have a metallic aftertaste. Ignoring these signals can lead to damage to more expensive elements of the system.
There are also visual signs that cannot be ignored. If you notice that scale has begun to appear on the walls of the kettle again, or the water has become cloudy immediately after opening the tap, this is an alarm bell. It is also worth paying attention to the manufacturers' recommendations, which usually indicate the service life in months or liters of filtered water.
⚠️ Attention: Operating the system with expired cartridges for more than 2-3 weeks can lead to the proliferation of bacteria inside the flasks and irreversible damage to the membrane.
To make it easier to control the timing of replacement, it is recommended to keep a simple maintenance log or stick stickers on the system body with the date of installation of new elements. This is especially true for those who use water irregularly or seasonally.
Types of filter elements and their purpose
Before you begin replacement, it is important to clearly understand which element is responsible for what in your system. A standard reverse osmosis circuit typically consists of five purification stages, each of which performs a unique function.
The first three steps are prefilters. They protect the thin membrane from mechanical damage and chlorine. Usually this is a polypropylene cartridge (mechanical cleaning), a coal briquette and again fine polypropylene. They take the brunt of pollution.
The fourth element is itself reverse osmosis membrane. It has the highest degree of filtration (0.0001 microns) and removes heavy metal salts, viruses and bacteria. This is followed by the fifth stage - a post-filter with activated carbon, which improves the organoleptic properties of already purified water.
| Cartridge type | Resource (months) | Function | Signs of wear |
|---|---|---|---|
| Polypropylene (PP) | 3-6 | Mechanical cleaning | Pressure drop, color change |
| Coal (CTO/GAC) | 6-12 | Removal of chlorine and organic matter | Chlorine smell |
| Membrane (RO) | 18-24 | Removing salts and viruses | Increase in TDS, slow tank build-up |
| Post filter (T33) | 12 | Improved taste | Unpleasant taste of water |
Different manufacturers may use different housing standards, e.g. Slim Line or standard 10-inch flasks. It is important to select replacement modules that match the dimensions and connection type of your specific model.
What is a TDS meter and why is it needed?
A TDS meter is a device for measuring the total salt content of water. With its help, you can objectively evaluate the effectiveness of the membrane. If the TDS of purified water has increased sharply compared to the indicators of the new membrane, then it is time to change it.
Preparing for replacement: tools and safety precautions
Replacing filters is a procedure that does not require sophisticated equipment, but requires care. You will need a minimum set of tools that can be found in every home. The main thing is to ensure that the workplace is clean so that no dust or dirt gets inside the system.
For work, prepare a basin or bucket for draining remaining water, towels or rags for wiping the surface, as well as a special wrench for unscrewing the flasks. If you do not have a special key, you can find one included with the system or purchase it separately at a plumbing store.
- 🛠️ Special key holder for plastic flasks (usually included).
- 🧼 Disinfectant or alcohol for treating the neck of the flask.
- 🧤 Disposable gloves for maintaining hygiene when in contact with filters.
- 📏 Capacity for measuring water volume (optional, to check performance).
Before starting work, be sure to turn off the water inlet valve to the system and open the clean water tap at the kitchen sink. This is necessary to relieve pressure in the line. If the system has an electric pump, be sure to unplug it.
☑️ Ready to replace filters
Step-by-step instructions: how to replace pre-filters
Replacing pre-clean cartridges is the most common procedure. Start by removing the flasks. Using a special wrench, carefully unscrew the first flask counterclockwise. Be prepared for some water to spill out of the flask, so keep a bowl directly underneath it.
Remove the old cartridge and thoroughly rinse the inside of the flask with warm water. Do not use harsh chemicals or abrasive sponges, as cleaning residues may end up in the drinking water. Inspect the rubber seals for cracks or deformation.
Install the new cartridge exactly in the center, making sure it sits tightly on the bottom. When screwing the flask back on, lubricate the rubber ring with food grade silicone grease to ensure a tight seal and ease of unscrewing in the future. Tighten the flask by hand until it stops, without overtightening it with a wrench.
⚠️ Attention: When tightening the flask, make sure that the rubber o-ring does not jump out of its groove or become skewed, otherwise the system will not be airtight.
Repeat the procedure for the second and third flasks if you are changing the entire set of prefilters at once. It is usually recommended to change all three stages of pretreatment at the same time to ensure an even load on the system.
In order not to confuse the order of installation of the flasks during assembly, change them one at a time or photograph the location of the tubes before disassembling.
Replacing the membrane and post-filter: the subtleties of the process
Replacing the reverse osmosis membrane requires more care. The membrane element is usually located in the fourth flask (or in a separate housing of larger diameter). Before removing the old element, be sure to close the taps on the storage tank.
Carefully remove the old membrane housing. Pay attention to the direction of water flow - there is always an arrow on the body indicating the direction of liquid movement. Installation of a new membrane must be manufactured strictly in accordance with this marking. An installation error will result in the system not working or the membrane failing instantly.
The post-filter (fifth stage) is often a flow-through cartridge type inline, which does not require unscrewing the flask. It is changed by disconnecting the tubes from the fittings. To do this, you need to press the plastic retaining ring around the tube and at the same time pull the tube out of the filter housing.
When installing a new post-filter, also observe the direction of flow indicated by the arrow on the housing. The tubes must fit into the fittings until they stop (approximately 15-20 mm). After installing all elements, the system must be flushed.
The main rule for replacing the membrane is to follow the direction of water flow indicated by the arrow on the element body.
Starting the system and checking for leaks
After installing all the new elements, the crucial launch moment comes. Open the water supply tap to the system and carefully observe the connections of the flasks and tubes. In the first minutes, dripping may be observed, which will disappear after the pressure equalizes.
Open the clean water tap in the kitchen. For the first 10-15 minutes, the water may come with air and have a black tint due to carbon dust - this is normal for new carbon filters. Drain approximately 10-15 liters of water to completely flush the system.
Check all connections for leaks by running a dry cloth over the joints of the bulbs and fittings. If the napkin remains dry, the system is assembled correctly. During the first 24 hours, it is recommended to periodically check the dryness under the sink.
- 💧 Open the tap and drain 2-3 full tanks of water to flush the system.
- 🔍 Visually inspect all connections for drips.
- 📉 Check the tank filling time - it should correspond to the norm for a new membrane.
⚠️ Warning: If you hear hissing or see air bubbles coming out of the water in the tank, this is normal. However, the constant sound of water pouring into the drain after turning off the tap indicates a malfunction of the valve.
Frequently asked questions (FAQ)
How long should I drain water after replacing filters?
It is recommended to drain at least two full volumes of the storage tank. This usually takes about 30-40 minutes of continuous draining. This is necessary to wash out the preservative from the new membrane and carbon dust from the post-filter.
Can polypropylene cartridges be washed and reused?
Absolutely not. The structure of polypropylene fiber is destroyed when contaminated, and washing does not restore its filtering properties. Repeated use will quickly contaminate subsequent purification stages.
Why does the water still have a taste after changing the filters?
New activated carbon may give off a slight aftertaste during the first hours of use. It is also possible that there is old water left in the tank. Try emptying the tank completely and waiting for a new set. If the taste persists for more than 2 days, check the connections for leaks.
Do rubber seals need to be lubricated?
Yes, it is recommended to do this with every replacement. Food-grade silicone grease prevents the rubber from drying out, makes it easier to unscrew the flask in the future and guarantees reliable sealing of the connection.