When you search for water purifiers on e-commerce platforms, your screen is flooded with claims like “99.9% bacteria removal,” “slightly alkaline water is healthier,” “mineralized filter cartridges replenish trace elements,” and “small-cluster water is easier to absorb”—each claim sounds more impressive than the last, as if installing this machine could turn tap water into some kind of miracle health elixir. But if you actually believe these marketing claims, you’re likely throwing your money away. In 2025, the State Administration for Market Regulation launched a special campaign targeting drinking water treatment equipment, naming and penalizing multiple companies for false advertising—including mislabeled germ removal rates, exaggerated claims, and forged certifications. Today, we’ll debunk the six most common marketing tricks in the water purifier industry one by one, helping you figure out which specifications are worth paying attention to and which sales pitches you can safely ignore.
A TDS tester is the most basic water quality testing tool; for just a few dozen yuan, you can determine whether your water purifier is working properly.
Tactic 1: “99.9% Bacteria Removal Rate”—Laboratory Data Does Not Equate to Real-World Results
This is the most frequently cited figure in water purifier advertising; nearly every product claims a “99.9% bacterial removal rate.” Yet few people question how this figure is derived. In fact, this number comes from tests conducted under laboratory conditions on specific bacterial strains—typically E. coli or Staphylococcus aureus—and is measured at specific concentrations, water temperatures, and pressures. The total bacterial count in your tap water is already quite low—municipal tap water standards require that the total bacterial count not exceed 100 CFU/mL, and in reality, most readings are below 10 CFU/mL. In other words, even if a machine can remove 99.9% of bacteria in a laboratory setting, this figure has very limited practical significance when applied to tap water that already contains very few bacteria.
What truly matters is the filtration precision of the RO or ultrafiltration membranes, not the marketing figure of the bacterial removal rate. The 0.0001-micron pore size of an RO membrane is inherently capable of physically trapping all bacteria and viruses—this is determined by its structural principles and requires no additional promotion.
Tactic #2: “Slightly alkaline water is healthier”—no authoritative medical evidence
Many water purifiers advertise that “the output water has a pH of 7.5–8.5, and slightly alkaline water is healthier,” even implying that slightly alkaline water can regulate the body’s constitution and prevent disease. But the fact is, there is currently no authoritative medical research proving that slightly alkaline water is beneficial to human health. The World Health Organization has never recommended drinking slightly alkaline water, nor has the Chinese Nutrition Society issued any related recommendations. The body’s acid-base balance is strictly regulated by the kidneys and the respiratory system; the pH of the water you drink has a negligible effect on blood pH. Normal human blood pH remains stable between 7.35 and 7.45 and will not change simply because you drink a few glasses of slightly alkaline water. Some water purifiers are equipped with “slightly alkaline filter cartridges” that release minerals to raise the pH of the filtered water. The lifespan of these cartridges is typically only 3 to 6 months; once they expire, the water returns to a neutral pH—meaning you’ve essentially paid for a three-month gimmick.
RO (reverse osmosis) membrane filters, with a filtration precision of 0.0001 microns, physically block all bacteria and viruses—there’s no need to rely on “bacteria removal rates” as a marketing gimmick.
Tactic #3: “Mineralization filters replenish trace elements”—“You’re better off just eating a bite of vegetables.”
“RO membranes filter too thoroughly, removing minerals as well, so a mineralization filter is needed to replenish them”— —This sales pitch has led many people to spend extra money on mineralization filter cartridges. But a quick calculation reveals that the amount of minerals released by these cartridges is extremely small. Take calcium as an example: the calcium content in mineralized water is generally between 2 and 10 mg/L. An adult’s daily calcium requirement is 800 mg, so you’d have to drink 80 to 400 liters of mineralized water just to meet your daily calcium needs. To put this in perspective: 100 grams of tofu provides 164 mg of calcium, and a glass of milk provides 120 mg, whereas one liter of mineralized water provides only 2 to 10 mg. Relying on water to replenish minerals is so inefficient as to be negligible. Research from the National Institute for Nutrition and Health at the Chinese Center for Disease Control and Prevention also indicates that minerals in drinking water contribute less than 5% to the body’s total mineral intake; the body’s mineral intake relies primarily on food. Therefore, rather than spending money on mineralized filter cartridges, it’s more practical to simply eat a few more bites of vegetables or drink an extra sip of milk.
Tactic 4: “Small-cluster water is more easily absorbed”—utter pseudoscience
Some water purifiers claim that technologies such as “magnetization,” “far-infrared,” and “electrolysis” can break down water clusters into smaller units, making them “easier for cells to absorb.” This claim has been repeatedly debunked by the academic community. The size of water clusters rapidly rearranges within the body; regardless of whether the water clusters you drink are large or small, they will recombine once they enter the digestive tract. The concept of so-called “small-cluster water” is not recognized by the mainstream scientific community, and there are no peer-reviewed studies proving any health benefits. Such marketing often cites the “research findings” of a certain Japanese scholar, but tracing the source reveals that the so-called experiments had extremely small sample sizes, lacked control groups, and have never been published in mainstream international academic journals. When you encounter claims about “small-cluster water,” just ignore them.
NSF International certification is one of the most authoritative third-party certifications in the water purifier industry—it’s more trustworthy than any marketing pitch.
Tactic 5: “Imported RO Membranes”—Domestic Membranes Posing as Imported Ones Are Not Uncommon The global RO membrane market is primarily dominated by three major brands: Dow (FilmTec) from the U.S., Hydranautics, and Toray from Japan. Many water purifiers advertise that they “use imported Dow RO membranes” or “Hydranautics membranes,” but industry insiders know that the RO membranes used in low-priced models are almost exclusively domestically produced. Domestically produced membranes aren’t necessarily inferior—their quality has improved rapidly in recent years, with desalination rates now exceeding 95%, narrowing the gap with imported membranes. However, the problem lies in passing off domestically produced membranes as imported ones, which constitutes false advertising.
It’s easy to tell the difference: check the brand logo and country of origin marked on the RO membrane. Genuine imported membranes will have clear brand logos, model numbers, and country of origin information. If a machine’s promotional materials simply state “imported membrane” but the actual filter cartridge lacks the corresponding brand markings, it’s most likely a counterfeit. Furthermore, it is virtually impossible for an RO system priced below 1,500 yuan to use genuine imported membranes—the cost of a single Dow 75G membrane alone is over 200 to 300 yuan, which the price of the entire unit simply cannot support.
The rated total water purification capacity on the product nameplate is a key parameter for determining the actual lifespan of the filter cartridge.
Tactic 6: “Zero Wastewater”—A False Claim That Violates the Principles of RO
The working principle of reverse osmosis (RO) dictates that pure water and concentrate must be produced simultaneously—water passes through a semi-permeable membrane under pressure, and the retained impurities are discharged with the concentrate. This is a law of physics; “zero wastewater” is impossible. Claims of “zero wastewater” can only arise in two situations: First, the unit is not an RO system at all but an ultrafiltration (UF) system; UF does indeed produce no wastewater, but its filtration precision is an order of magnitude lower. Second, the concentrate is discharged directly into the sewer without passing through a recovery line—you simply haven’t noticed it. Some brands use slogans like “wastewater ratio接近 zero” or “wastewater can be recycled,” which are entirely different from “zero wastewater.” “Recyclable wastewater” refers to diverting the concentrate to a washing machine or toilet tank for reuse—which is indeed a water-saving practice—but it does not actually reduce the volume of wastewater produced. When you see “zero wastewater” claims, first verify whether the unit is actually a reverse osmosis (RO) system. If it is, then that claim is simply misleading.
Given the actual ratio of purified water to wastewater produced, an RO system cannot achieve “zero wastewater.”
When reviewing water purifier specifications, focus on just three key metrics
To avoid all the marketing tricks mentioned above and assess a water purifier’s actual performance, you only need to look at three key metrics.
The first is the rated water purification capacity. This parameter is listed on the product nameplate and refers to the total volume of qualified purified water the filter cartridge can process over its lifespan. For example, a rated water purification capacity of 2,000 liters means that under nominal conditions, the filter cartridge only needs to be replaced after the machine has cumulatively produced 2,000 liters of purified water. The higher this value, the longer the actual service life of the filter cartridge and the lower the average annual cost of consumables. Some low-cost models list a rated water purification capacity of only 1,000 to 1,500 liters, while mid- to high-end products generally range from 2,000 to 4,000 liters or more—a very noticeable difference.
The second is the wastewater ratio. According to the national standard GB34914-2021, water efficiency is divided into three grades: Grade 1 requires a pure water recovery rate of at least 65% (approximately a wastewater ratio of 2:1), Grade 2 at least 55% (approximately 1.2:1), and Grade 3 at least 45% (approximately 0.8:1). When purchasing an RO system, choose at least Grade 2 water efficiency, with Grade 1 being the preferred option. The wastewater ratio directly affects your tap water consumption.
Third is certification. In China, look for the health permit (Weishui Zi); this is a mandatory requirement for products to be sold on the market—do not purchase products without this permit. Among international certifications, the NSF/ANSI standards are the most authoritative third-party certifications in the water purifier industry, particularly NSF Standard 58 (Reverse Osmosis Drinking Water Treatment Systems) and NSF Standard 53 (Health Effects of Drinking Water Treatment Devices). Models with these two certifications have performance metrics that stand up to scrutiny.
A water purifier is a home appliance, not a health supplement. It only addresses the issue of “water safety”—removing harmful substances from the water so you can drink clean, safe water. It does not address the issue of “water wellness”—concepts like “slightly alkaline,” “mineralization,” and “small water clusters” are essentially marketing gimmicks in the water purifier category. It is far wiser to spend less on a water purifier with solid specifications and complete certifications than to spend more on a “health-promoting water machine” full of gimmicks.
⚠️ Disclaimer: The content of this article is for reference only and does not constitute any advice regarding consumer decisions. The analysis of marketing tactics mentioned in this article is based on publicly available market information and regulatory bulletins; for specific product evaluations, please refer to official specifications and test reports. Regarding concepts such as slightly alkaline water and mineralized water, please rely on the research conclusions of authoritative medical and scientific institutions.
Translated with DeepL.com (free version)
