Water purifier emitting an odor? Without identifying these 5 “sources of stench,” replacing the filter cartridge is pointless!
You're about to brew tea when a pungent plastic smell hits you. Or you take a sip of cold boiled water in the morning only to detect a faint fishy taste. When water from your purifier smells off, most people immediately think, “Time to replace the filter.” But if the odor persists after changing it, you've just wasted your money!
Actually, foul-smelling water isn't just a filter cartridge issue. Today we'll break down the 5 most overlooked “sources of odor,” each with a “1-minute troubleshooting method” and “step-by-step solution.” After reading, you can tackle the problem yourself and enjoy clean, odor-free water! If you find this helpful, give it a thumbs up!
01. Cause 1: New filter hasn't been “activated,” residual preservative causes plastic smell
Odor characteristics: Noticeable plastic smell or faint chemical odor after replacing the filter. Water isn't cloudy and lacks fishy/musty odors. Why does this happen? Activated carbon filters come coated with a “protective solution” (to prevent moisture damage during shipping). If installed immediately, this solution leaches into the water, causing the plastic smell. New water pipes may also emit a mild plastic odor initially due to their material.
Troubleshoot + Fix Recall if you recently replaced the filter (especially the activated carbon one) or installed a new machine/new pipes. Turn on the purifier faucet and let water flow continuously for 15-20 minutes (don't worry about wasting water!). Sniff the water every 3 minutes until the odor completely disappears. If the new pipe smell is strong, disconnect both ends of the pipe, rinse them under the faucet for 10 minutes, then reinstall them—this will eliminate the odor faster. Important tip: Do not use dish soap to clean new filters or new pipes! Detergent residue will linger and make the odor harder to eliminate.
02. Cause 2: Activated Carbon Filter “Saturation” – Adsorption Failure Releases Odors
After 6-12 months of use, water may develop a sour, rotten smell or taste like untreated water (e.g., chlorine from tap water), with odors gradually worsening. Activated carbon filters remove odors (like chlorine or organic compounds) through adsorption. Like a sponge, they have a capacity limit—typical household filters reach saturation after 6-12 months. Continuing use causes them to “release” previously absorbed odors, resulting in foul-smelling water. Troubleshooting + Solution
Check the filter replacement log. If the activated carbon filter hasn't been replaced in over 6 months, or if it feels “heavy” when pressed (indicating it's saturated with impurities), it's likely the culprit. Replace directly with the same model activated carbon filter (be careful not to buy the wrong one! Pre-filter carbon and post-filter carbon are different; post-filter carbon handles final odor removal and should be replaced first). After replacement, follow the method in Reason 1: let water run for 10 minutes to ensure the new filter's protective solution is thoroughly flushed out. Tip: For households with poor water quality or high water usage, it's recommended to shorten the activated carbon filter replacement cycle to 4-6 months to prevent premature saturation.
03. Cause 3: Water Tank “Harbors Contaminants” – Mold/Stale Water Causing Fishy Odor
Noticeable fishy or musty taste in the water, especially pronounced in the first cup of water in the morning. The odor lessens after draining half the tank. Water storage tanks in purifiers create a sealed, humid environment:
- If water remains unchanged for extended periods (e.g., after a week-long trip), it becomes stagnant and breeds bacteria.
- Aging seals around the tank opening allow mold to enter through cracks, causing foul odors.
Troubleshooting + Solutions
1. Open the tank's vent valve (usually on top) and check for moldy smells.
or pour a cup of water from the tank, let it sit for 5 minutes, and check for floating particles. First, drain the water from the storage tank (open the faucet until no water comes out).
Prepare a cleaning solution using a ratio of “1 liter of water + 10ml of food-grade disinfectant” (such as chlorine dioxide effervescent tablets). Pour it into the tank through the opening, tightly close the lid, shake for 30 seconds, and let it soak for 10 minutes.
Drain the cleaning solution, then rinse the tank thoroughly with clean water three times. Finally, fill it with water once and drain it completely. This will eliminate any lingering odors. Important reminder: Do not use 84 disinfectant! It leaves a chlorine odor and may corrode the plastic tank.
04. Cause 4: Heating Module Scaling and Bacterial Growth, Emitting Burnt Odor
Only hot water has an unusual taste (e.g., burnt or bitter flavor), while cold water remains normal; or the machine emits a faint “hissing” sound during heating, and the water tastes bitter.
In water purifiers with heating functions, heating elements accumulate scale over time (especially in hard water areas). Scale buildup coats the heating element, causing localized overheating and producing a burnt smell. Simultaneously, bacteria thrive in scale crevices, imparting a bitter taste to hot water.
Troubleshooting + Solution
Inspect the heating element surface (if the unit is disassemblable) for white scale deposits;
or fill a cup with hot water, let it cool, and check for sediment at the bottom;
Disconnect power and drain water from the heating tank;
Prepare a descaling solution using “1 liter water + 20g citric acid,” pour it into the heating tank, and soak for 30 minutes (soak for 1 hour if scale is thick); drain the solution, rinse the tank twice with clean water, refill with water and heat once more, then drain. This will eliminate odors and scale. Prevention Tips: In hard water areas, install a pre-filter to reduce scale buildup; clean the heating module monthly with citric acid to extend its lifespan.
05. Cause 5: “Contaminated” Water Source / Inlet Pipes Overwhelm the Water Purifier
No matter how many times you replace the filter cartridges or rinse the storage tank, the water still has an iron rust or earthy taste. This issue is also present in neighboring homes (e.g., after water supply resumes following a community water outage). The odor isn't caused by the water purifier, but by the household water pipes or the community's water supply system: for example, aging and rusting pipes in the community, or sediment and microorganisms entering the pipes after a water outage. Water purifiers can only filter impurities and cannot completely remove the rusty or earthy taste originating from the pipes.
Troubleshooting + Solution
1. Turn on a tap in your home (one not connected to the water purifier) and check if it has the same odor. If it does, the issue lies with the water source or pipes. First, let the tap run for 10-15 minutes (to flush out dirty water from the pipes), then use the water purifier to see if the odor lessens. If the rusty smell is noticeable, install a “pre-iron removal filter” before the water purifier. Alternatively, contact property management to report aging pipes and request replacement. Emergency Fix: For temporary odors, add an activated carbon filter tablet (available at pharmacies) to the purified water, let it sit for 5 minutes before drinking. This temporarily absorbs the odor.
06. Odor Troubleshooting “Priority”: 3-Step Rapid Diagnosis
If unsure of the cause, follow this sequence for efficient and accurate identification:
First check: “Has the filter cartridge been recently replaced / Is it a new unit?” → Corresponding cause 1 (flushing the filter cartridge);
Then check “Does the odor occur in cold or hot water?” → If hot water: Reason 4 (descaling); if cold water: Reasons 2/3;
Finally check “Does the neighbor's unit have an odor?” → If yes: Reason 5 (run tap water); if no: Reason 3 (clean the storage tank).
07. Daily Prevention: 3 Tips to Keep Odors Away
Even when not using water, open the purifier faucet weekly and let water run for 5 minutes to prevent stagnant water in the storage tank from breeding bacteria. Check if the activated carbon filter has discolored (from black to gray) or if the storage tank has a musty smell—early detection means early action. After water service resumes in your neighborhood, let tap water run for 10 minutes before using the purifier to avoid dirty water from pipes entering the machine. Final reminder:
If odors persist after troubleshooting and the water has a pungent smell (like disinfectant or bitter almonds), do not drink it! This could indicate internal damage (e.g., a ruptured RO membrane). Contact the brand's after-sales service immediately for professional inspection—safety comes first.
What kind of odors has your water purifier produced? How did you resolve it? Share your experiences in the comments to help others avoid pitfalls!
【Rumor Buster】Water Purifiers: What You Absolutely Must Know!!
