How to choose flow rate? What is a good wastewater ratio? How much do replacement filters cost? Are instant hot purifiers worth it? Brand comparison.
Water purifiers have gradually become a standard kitchen appliance in Chinese households, but the market offers everything from a few hundred yuan to six or seven thousand yuan, with terms like RO reverse osmosis, ultrafiltration, and nanofiltration making it all very confusing. I’ve replaced my water purifier three times over the years, starting with a Xiaomi 400G and later upgrading to a Midea Baize 1000G—I’ve stepped on landmines and also saved money. In this article, I’ll break down every key parameter of water purifier selection so that after reading it, you can judge for yourself which model is right for your home.
This is the most central question when buying a water purifier. The essential difference between the three technologies lies in filtration精度 and desalination rate.
RO Reverse Osmosis: Filtration精度 up to 0.0001 microns, equivalent to one millionth of a human hair. RO membranes can remove heavy metals (lead, mercury, chromium, cadmium, etc.), bacteria, viruses, pesticide residues, antibiotics, scale (calcium and magnesium ions), and virtually all harmful substances from water. The output is pure water, with TDS typically below 10. RO reverse osmosis is currently the most mature and safest home water purification solution. The downside is that it produces wastewater and removes minerals from the water. I strongly recommend most families choose an RO reverse osmosis water purifier—safety first.
Ultrafiltration UF: Filtration精度 of 0.01 microns, capable of removing sediment, rust, bacteria, and most colloids, but cannot remove heavy metals, viruses, or scale. The advantages are no electricity required, no wastewater produced, and retention of minerals. Suitable for areas with good tap water quality (TDS below 200), or as a pre-filter before an RO system. In northern areas with hard water, ultrafiltration alone is not recommended—it won’t solve the scale problem.
Nanofiltration NF: Filtration精度介于 RO and ultrafiltration之间, approximately 0.001 microns. Nanofiltration can selectively remove some hardness ions (calcium, magnesium) and heavy metals while retaining some minerals. It sounds great, but in practice, the desalination rate of NF membranes is not consistently controlled and varies greatly between manufacturers. Moreover, NF prices are not significantly cheaper than RO, so I personally don’t recommend the NF solution.
Tap water TDS above 200 (most of northern China): go directly with RO reverse osmosis, no hesitation.
Tap water TDS below 100 (some high-quality water sources in southern China): you could consider ultrafiltration, but I recommend doing a water quality test first.
Ample budget, want better-tasting water: choose RO reverse osmosis + post-activated carbon (to improve taste).
Note: TDS is only a reference indicator and does not represent water safety. Even with low TDS, there may still be heavy metal risks.
Flow rate (unit: gallon G) represents the water production capacity of the purifier under continuous 24-hour operation. 1 gallon is approximately 3.785 liters. The higher the flow rate, the faster the water output and the shorter the wait time.
400G: Output speed of about 1.0 liters/minute, filling a cup (250ml) takes about 15 seconds. Suitable for 1-2 people, lowest price (1,000-1,500 yuan), but the wait time for water is longer. If your household has few people and low water usage, 400G is sufficient.
600G: Output speed of about 1.5 liters/minute, filling a cup takes about 10 seconds. Suitable for 2-3 person households, currently the best value flow rate. Prices range from 1,500-2,000 yuan.
800G: Output speed of about 2.0 liters/minute, filling a cup takes about 7-8 seconds. Suitable for 3-4 person households, the output speed is already quite comfortable. 800G is also the most mainstream flow rate with the widest brand selection.
1000G: Output speed of about 2.5 liters/minute, filling a cup takes about 5-6 seconds. Suitable for 4+ person households or those who demand faster water output. Prices range from 2,000-3,000 yuan. The Midea Baize 1000G and Xiaomi MR1082 are representative models at this level.
1200G and above: Output speed of 3.0 liters/minute or more—almost no waiting for water. However, currently, 1200G models and consumables have limited options and prices are high (above 3,000 yuan), so they’re not yet mainstream. Unless your household is particularly large (5+ people), 1000G is already more than enough.
RO reverse osmosis water purifiers produce “wastewater” (concentrated water) while making pure water. The wastewater ratio通俗地说 is “how much wastewater is discharged for every cup of pure water produced.”
Wastewater ratio: Older RO models typically had a 1:1 ratio (1 cup pure water to 1 cup wastewater). Current mainstream models have achieved 2:1 to 3:1—producing 2-3 cups of pure water for every 1 cup of wastewater. Some high-end models claim 4:1 or even 5:1, but I’ve found in actual testing that the wastewater ratio is heavily affected by water temperature and pressure. In winter when water temperatures are low, the ratio drops noticeably. 2:1 or higher is already very good—there’s no need to excessively pursue ultra-high wastewater ratios.
Filter replacement cost is the real “long-term bill” for water purifiers. Many people only look at the cheap machine price and buy it, only to find that the annual filter replacement cost is higher than the machine itself. Water purifiers generally have three to four stages of filters:
All things considered, the annual filter replacement cost for an RO water purifier ranges from 400-800 yuan. This varies greatly between brands: Xiaomi’s filters have transparent pricing (annual cost about 400-500 yuan), Midea’s Baize series claims the RO membrane lasts 5 years (but actually about 3 years), and Qinyuan’s filters are pricier (annual cost about 600-800 yuan).
Some brands sell the machine very cheap (for example, some internet brands sell RO machines for 999 yuan), but the filters are non-standard规格, so you can only buy their expensive proprietary filters, pushing annual costs to 800-1,000 yuan. After two years, that’s more expensive than buying a major brand machine.
I recommend优先 choosing models that use通用 filters, or brands with transparent filter pricing that doesn’t exceed the industry average. Xiaomi, Midea, and Qinyuan all have transparent filter pricing, so you can buy from them with confidence.
Also note: some brands advertise “no filter change for three years,” but in practice, the pre-filters still need to be replaced on schedule, otherwise the RO membrane lifespan will be greatly shortened.
Instant hot water purifiers (also called净饮一体机) combine RO water purification with instant heating, allowing you to get hot water directly—very convenient for making tea, baby formula, or coffee. These products have been very popular in 2024-2025, but they also have some明显的 drawbacks.
Advantages: Instant hot water, multi-temperature control (room temperature, 45°C for formula, 85°C for tea, 100°C boiling), no need for a kettle or thermos, clean and tidy countertop. Suitable for families with babies who need frequent bottle preparation, or for office, bedroom, and other places where plumbing access is inconvenient.
Disadvantages: Water output is slower than regular under-sink purifiers (the instant heating module restricts flow rate), generally only 0.5-1.0 liters/minute. The water tank capacity is limited (usually 4-6 liters) and requires manual refilling, making it unsuitable for high-volume water usage scenarios. Prices are on the high side (2,500-5,000 yuan), and the machine is bulky, taking up counter space. Filter replacement frequency is higher, and annual costs are also higher.
My advice: If you have enough kitchen space, the preferred solution is a combination of an under-sink RO water purifier + a separate dispenser or instant hot water dispenser. The under-sink purifier produces pure water, and the dispenser handles heating—分工明确, fast water output, low maintenance costs. Instant hot water purifiers are more suitable for rental apartments, offices, or situations where kitchen space is very limited.
Under-sink: Installed under the kitchen sink, connected to the cold water line, with a dedicated purified water faucet. Doesn’t take up counter space, high water production capacity, long filter life. This is the most recommended method for home water purification. The downside is that it requires some space under the cabinet, and installation may require drilling after renovation is complete.
Countertop: Placed directly on the kitchen counter, connected via a faucet diverter or独立 water tank. Simple installation, no drilling required, suitable for renters or those who can’t easily modify their kitchen. But it takes up counter space and is less aesthetically pleasing than the under-sink method.
Faucet-mounted: Installed directly on the faucet, smallest size, lowest cost (100-300 yuan). But filtration精度 is usually not high (mostly ultrafiltration or microfiltration), filters need frequent更换, and it affects normal faucet use. Only suitable for temporary过渡 use, not recommended as a long-term home water purification solution.
Below, I’ve put together a comparison of the four most popular RO reverse osmosis water purifiers on the market for your direct reference.
| Brand/Model | Flow Rate | Reference Price | Output Speed | Wastewater Ratio | RO Membrane Life | Annual Filter Cost | Special Features |
|---|---|---|---|---|---|---|---|
| Midea Baize 1000G | 1000G | 2,299 yuan | 2.5L/min | 2:1-3:1 | 5 years (claimed) | ~450 yuan | Dual water output, TI touch faucet, 5-year long-life RO membrane |
| Xiaomi MR1082 | 1000G | 1,799 yuan | 2.5L/min | 2:1-3:1 | 3 years | ~499 yuan | Mi Home app smart control, OLED display faucet, best value |
| Qinyuan QR-RF-1002 | 1000G | 2,699 yuan | 2.5L/min | 1.5:1-2:1 | 3 years | ~600 yuan | Professional water purification brand, stable filtration, extensive service network |
| Joyoung JYW-RF681 | 800G | 1,599 yuan | 2.0L/min | 2:1-3:1 | 3 years | ~400 yuan | Affordable price, dual water output, stainless steel faucet |
| Brita BR-RF-2000 | 600G | 1,399 yuan | 1.5L/min | 1.5:1 | 2 years | ~350 yuan | German brand, EU-certified filters, compact size |
Brand Reviews:
Midea Baize 1000G (2,299 yuan): This is the model I currently use myself, and after nearly a year and a half, I’m very satisfied. What attracted me most is the 5-year long-life RO membrane (in实际使用, the衰减确实不明显), bringing the annual filter cost down to just around 450 yuan. The dual water output design is also very practical—one side produces pure water (for drinking/cooking), the other produces filtered water (for washing vegetables/dishes). The TI touch faucet feels premium and shows real-time TDS readings. If your budget is in the 2,000-2,500 yuan range, the Baize 1000G is the most comprehensive recommendation.
Xiaomi MR1082 (1,799 yuan): The lowest-priced model in the 1000G flow rate category, the king of value. The Mi Home app allows real-time monitoring of water quality, water usage, and filter life, and can also schedule timed flushing. Output speed and wastewater ratio are comparable to the Midea Baize. The downsides are that the RO membrane life is rated at 3 years (实 maybe 2 years), and the after-sales installation experience varies by region. If you’re already in the Mi Home ecosystem, the MR1082 is a no-brainer choice.
Qinyuan QR-RF-1002 (2,699 yuan): Qinyuan is a long-established professional water purification brand with stable and reliable filtration效果. The filter stage design of the QR-RF-1002 is reasonable, and the output water tastes the best among the models I’ve tried. However, the price is on the higher side, and the wastewater ratio is relatively conservative (1.5:1-2:1), and the smart features are not as rich as Xiaomi or Midea. Suitable for those who value filtration效果 more than smart features.
Joyoung JYW-RF681 (1,599 yuan): Although Joyoung is not a professional water purification brand, this 800G machine offers great value. Dual water output design, stainless steel faucet, easy filter更换, with annual filter cost around 400 yuan. Suitable for budget-sensitive users, and the 800G flow rate is fully sufficient for a family of three.
There are a few easily overlooked details when installing a water purifier that I learned the hard way:
First, check before buying whether there’s a power outlet under your cabinet. RO purifiers need electricity (for the booster pump and smart faucet). If there’s no outlet, you’ll have to choose ultrafiltration or run exposed wiring.
Second, measure the dimensions under your cabinet. Older tank-style RO machines require more space. Current mainstream large-flow tankless models are much smaller, but you still need to confirm whether the height and depth are sufficient. The Midea Baize 1000G measures 460x420x140mm, which fits in most cabinets.
Third, if you’re doing new renovations, I recommend预留 an electrical outlet and a drain pipe (for wastewater) under the kitchen sink, and also确定 the opening位置 for the purified water faucet in advance (usually next to the sink or on the countertop).
Fourth, if you choose an instant hot water净饮一体机, it needs to be placed on the countertop, so measure your counter space in advance to ensure the machine fits. Instant hot water machines are usually quite bulky, typically 30-40cm wide.
Fifth, after installation, it’s recommended to let the water run for 20-30 minutes to flush out the保护液 from the new filters before drinking. When using an RO machine for the first time, you may see small black particles in the water—those are debris from the new activated carbon filter. They’ll clear up after a few flushes; this is normal.
Best overall value: Xiaomi MR1082 (1,799 yuan) — 1000G flow rate, smart connectivity, low annual filter cost, suitable for most families.
Best overall quality: Midea Baize 1000G (2,299 yuan) — 5-year long-life RO membrane, dual water output, touch faucet, most worry-free for long-term use.
Budget-limited首选: Joyoung JYW-RF681 (1,599 yuan) — 800G flow rate is sufficient, cheap filters, great entry-level choice.
Pursuing filtration效果: Qinyuan QR-RF-1002 (2,699 yuan) — Professional water purification brand, best-tasting output water.
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