Many of my friends complain that their home water purifiers start to slow down or occasionally leak after less than two years of use—replacing a filter cartridge costs several hundred yuan, and they have to wait for a technician to come out for repairs. Where does the problem lie? In over 90% of cases, it’s not a quality issue with the product itself, but rather a lack of proper daily maintenance. A water purifier isn’t a device you can just install and forget about—by following these three steps, you can prevent most malfunctions.
Replace the pre-filter on time—don’t wait until the water flow slows down
The most common reason people call for repairs is that the water flow keeps getting slower. Most people’s first thought is that “the RO membrane is failing,” but upon inspection, nine times out of ten, it’s because the pre-filter PP cotton or activated carbon has become clogged. Pre-filters serve as the first line of defense for the RO membrane: the PP cotton filter traps large particles such as silt and rust, while the activated carbon adsorbs residual chlorine and organic compounds. Once they become saturated and fail, not only does the water flow rate drop sharply, but residual chlorine will also penetrate the pre-filters and directly attack the RO membrane—the RO membrane has extremely low tolerance for chlorine, and prolonged exposure will accelerate membrane aging, cause TDS levels to skyrocket, and effectively cut its lifespan in half.
Many people rigidly follow the “PP cotton every 6 months, activated carbon every 12 months” replacement schedule, but this approach is actually not very precise. The replacement cycle depends on two variables: the quality of the source water and daily water consumption. In northern regions with hard water or for residents at the end of the pipeline network in older neighborhoods, the PP cotton may turn yellow and become dirty in as little as 3 months; whereas in southern regions with softer water or for users in newer neighborhoods, the PP cotton may last up to 8 months without any issues. The correct way to determine when to replace it is to periodically open the filter housing and check the color of the PP cotton—if the surface appears yellow, brownish, or has noticeable sediment buildup, it’s time to replace it; there’s no need to strictly adhere to a set timeframe.
Determining when to replace the pre-filter activated carbon is somewhat more complicated, as its appearance doesn’t change significantly once it becomes saturated. Here’s a practical tip: pour a glass of filtered water and take a whiff. If you detect a faint smell of bleach (residual chlorine), it means the activated carbon has reached adsorption saturation and needs to be replaced. If possible, use residual chlorine test strips for a more precise confirmation; the detection of residual chlorine in the filtered water indicates that the pre-filter activated carbon has failed.
💡 The replacement cost for PP cotton and the pre-filter activated carbon is typically only about one-tenth that of an RO membrane. Don’t let the RO membrane fail prematurely just to save a few dozen yuan—it’s not worth sacrificing the bigger picture for a small saving.
RO Membrane Flushing: Know How to Use Both Automatic and Manual Methods
During operation, impurities on the concentrate side of the RO membrane continuously become more concentrated. If these concentrates aren’t flushed out promptly, they’ll form scale on the membrane surface, leading to a decrease in desalination rate and reduced water output. This is the fundamental reason why RO membranes need to be flushed. Currently, the vast majority of RO systems feature an automatic flushing function—they automatically flush for 10–30 seconds after each water production cycle, and some models also trigger a forced flush after a certain cumulative operating time. This function generally requires no user intervention, but there is one thing to verify: whether your water purifier is performing automatic flushing properly. The simplest way to check is to listen for the machine’s operating sound (which usually lasts about ten seconds) after water production has finished. If you don’t hear it, there may be an issue with the flushing program, and we recommend contacting customer service for an inspection. Manual flushing is recommended in several specific situations: after returning from an extended absence (when the system has been idle for more than a week), you should manually flush the system for 1–2 minutes before first use; after replacing the pre-filter, it’s also recommended to manually flush the RO membrane for at least 30 seconds to remove any residual carbon powder and air bubbles from the tubing; if you notice an abnormally high TDS value in the output water, manual flushing is the quickest way to troubleshoot the issue. The procedure varies by model—some have a “Flush” button on the unit itself, while others require pressing and holding a specific button on the faucet to trigger it. Please refer to the user manual for your specific model.
Regularly Inspect Pipe Connections—Small Leaks Can Lead to Major Problems
Another common issue with water purifiers is leaking pipe connections. RO systems primarily rely on quick-connect fittings and PE tubing for connections. After prolonged use, the PE tubing may age and harden, and the O-rings inside the quick-connect fittings may wear out, leading to minor seepage at best and flooding the cabinet at worst. These leaks rarely occur suddenly; instead, they seep slowly, and by the time they’re discovered, the bottom of the cabinet may have been saturated for quite some time. The self-inspection method is simple: every two months, open the cabinet door under the sink and feel the pipe connections and the bottom panel around the water purifier with your hand. If the connections feel damp or there are water stains on the bottom panel, it indicates a leak. Pay special attention to these areas: the connection between the inlet ball valve and the PE pipe; the quick-connect fittings between the filter cartridges; and the connection between the wastewater pipe and the drain pipe. If you find a leak, don’t delay—leaks at quick-connect fittings are usually caused by the PE pipe not being inserted deeply enough or by an aged O-ring. Simply reinsert the pipe or replace the fitting; the cost is only a few yuan.
Winter freeze protection and procedures for long-term disuse.
In northern regions and in installation settings such as balconies or garages without heated water, winter freeze protection is an issue that is easily overlooked. Once an RO membrane freezes, the membrane will suffer irreversible damage. When the ambient temperature is likely to drop below 0°C, you must insulate the water purifier or simply close the inlet valve and drain any remaining water from the piping and storage tank. The draining process is straightforward: close the inlet ball valve, open the purified water faucet to release pressure, and then open the drain valve at the bottom of the storage tank to empty the water inside. Similar precautions apply for extended absences (more than two weeks). Before leaving, close the inlet valve, disconnect the power supply, and drain the stored water. When reactivating the system upon your return, first open the inlet valve and let the machine produce water to flush the system for 5–10 minutes before drinking. If the system has been idle for more than a month, it is recommended to replace the pre-filter PP cotton—PP cotton left unused for an extended period may harbor bacteria, which could be flushed into the subsequent filter cartridges once water flow resumes.
How long a water purifier lasts depends 30% on the product and 70% on maintenance. Replace the pre-filter on schedule, don’t skip flushing the RO membrane, and inspect the pipe connections regularly—if you do these three things, it won’t be hard for your water purifier to run reliably for more than five years. Conversely, if you neglect it after installation, let filters run past their expiration dates, or ignore leaks, even the best machine won’t last. Spending a few minutes on maintenance is far more cost-effective than spending hundreds of yuan on repairs.
