Drinking “fake purified water” for three years! These hard-learned lessons ring all too true.

Hey dear friends, you know what I mean! Last week I popped round to a mate's place to swap her filter cartridge, and when I opened her water purifier, I was utterly gobsmacked! She said she'd shelled out ￡150 on that ultrafiltration machine, thinking she'd get clean water straight from the tap, but drinking it gave her the runs. Upon closer inspection, I realised the old neighbourhood's pipes were severely corroded, pushing the tap water's TDS level up to 420. Yet this ultrafiltration unit could only strain out sand and silt. Even worse, the water storage tank was overrun with green algae, thick as a lawn – a veritable bacterial breeding ground!

Having worked in this industry for eight years, I handle hundreds of complaints annually from people who chose the wrong water purifier. One customer spent ￡300 on a microfilter, only to find scale thick enough to scrape off after boiling water. Another bought a cheap, no-name RO system—after six months, the waste-to-clean water ratio was 1:3, costing an extra ￡50 monthly on water bills. Choosing a water purifier isn’t that hard. Just remember these four key parameters, and you’ll avoid ninety percent of pitfalls!

Sales pitches? Pure nonsense! These 4 parameters are what truly matter

When selecting a water purifier, ignore all the flashy marketing claims—things like ‘imported filter cartridges’ or ‘smart sterilisation’ are just noise. Focus on these 4 core parameters for reliability:

Filter Cartridge Type: Choosing the right filtration method is far more valuable than spending extra

There are only 4 major types of water purifiers on the market—choosing the wrong type means your money goes down the drain!

Microfiltration units (50-10,000nm): Frankly, these merely trap coarse particles like sediment and rust—think standard jug filters or tap attachments. Suitable only if you live in a new development with pristine water. Otherwise, forget it. Water remains undrinkable post-filtration, rendering it largely useless.

Ultrafiltration systems (2-100nm): These can block bacteria and viruses, but they're utterly useless against heavy metals and limescale. Avoid them entirely in hard water areas of northern China, where boiled water will be full of white scum. Families on a tight budget who only drink boiled water might consider them, typically costing ￡80-￡150.

Nanofiltration systems (0.5-5nm): Produces water with a crisp, sweet taste while retaining some minerals, ideal for households seeking ‘mineral water’. Pricier at 2000-4000 yuan, but ensure compliance with the new national water efficiency standards when purchasing.

Reverse osmosis systems (0.1-1nm): Employing aerospace-grade filtration technology, these units effectively remove nearly all impurities. Ideal for households with infants, those in areas with poor water quality (e.g., heavy metal contamination), or anyone preferring to drink filtered water directly. Currently the most popular on the market, priced between ￥1,500 and ￥5,000. Take Mrs Li from Haidian District, for instance: her previous ultrafiltration system tested positive for lead exceeding safety limits when replacing the filter cartridge!
Households with elderly members or children should heed this advice – opting for an RO reverse osmosis purifier is undoubtedly the right choice.

Flow Rate: Higher flow rates mean smoother operation—avoid ‘narrow pipes’

Flow rate is measured in gallons per minute (G), directly determining water output:
400G (1.05L/min): Suitable for 1-2 people in rented accommodation. Filling a cup takes about 8 seconds, which can be frustrating during peak usage times.

600G (1.58L/min): Perfect for 3-4 person households. Fills a cup in 5 seconds, ample for cooking and soups.

800G and above (2L/min+): Ideal for larger homes or those who prefer drinking filtered water straight from the tap. Flow matches mains water speed, though it costs a few hundred quid more.

Take my word for it! Avoid older models with storage tanks at all costs! I've seen the most extreme cases where the tank walls were covered in thick green algae that needed scraping off with a trowel. Modern tankless RO systems are both hygienic and space-saving.

Total Purified Water Capacity: This figure determines your long-term savings

Total purified water capacity indicates the maximum volume a filter cartridge can process. Higher values mean longer cartridge lifespan:

Low-end models: Typically around 1000L total filtration capacity. Cartridges need replacing every six months—twice a year—costing over ￡30 just for replacements.

Mid-to-high-end models: Capable of 4000L+ total filtration, some even reaching 6000L. Cartridges last two years, saving you ￡20 annually. Mr Wang from Tongzhou is particularly adept at crunching the numbers. He invested an extra ￡30 to purchase a model with a 6,000-litre total purification capacity. ‘Though it cost more upfront, the cartridge lasts two years – a cracking deal when you do the maths!’

Wastewater Ratio: Prevent Your Water Purifier from Becoming a “Water Guzzler”

The wastewater ratio indicates how much waste water is produced per litre of purified water. A higher ratio signifies greater water efficiency:

Older models: Typically exhibit a 1:3 ratio, meaning 3 litres of waste water are discharged for every 1 litre purified, adding approximately ￡20 to monthly water bills.

Newer models: Those meeting the latest national standards achieve at least 1.5:1, with mainstream units now reaching 2:1 or even 3:1 – saving both water and money. However, avoid chasing excessively high ratios; figures above 4:1 may shorten filter lifespan, which is simply unnecessary!

Families with infants and young children: Prioritise safe direct drinking water

Opt for reverse osmosis (RO) models, preferably those bearing ‘Infant and Child Safety Certification’. Choose filter cartridges from reputable imported brands like Dow or Hydranautics for enhanced filtration reliability. Ensure a minimum flow rate of 600G to avoid delays when preparing formula. Select units with a total purification capacity exceeding 4000L to reduce filter replacement frequency, offering greater safety for your baby.

Older Properties / High Floors: Address Water Pressure First

In older homes with low water pressure, select an RO system with a booster pump—otherwise, the slow flow rate will drive you mad. For high-rise buildings with secondary water supply systems and complex water quality, invest a few hundred pounds in a pre-filter to trap large particles. This extends filter life and saves over ￡100 annually on replacement costs.

Three essential pitfall-avoidance strategies

Lifetime filter replacement-free’ claims are pure nonsense

The most outrageous advert I've seen promised ‘no filter changes for ten years’ – don't fall for it! RO membranes last a maximum of three years, while activated carbon filters must be replaced every 6-12 months or they become breeding grounds for bacteria. Always ask the price per individual filter before buying. Some brands offer cheap machines, but with filters costing ￡50 each, they recoup the price difference within two years.

Even major brands have ‘substandard products’ – scrutinise inspection reports

Last year's spot checks exposed numerous big names: some falsely advertised total purification capacity, with actual filtration output half the claimed figure; others delivered water exceeding bacterial limits. When purchasing, request the latest inspection report from sales staff. Focus on ‘total purification capacity’ and ‘output water quality’ – only buy if both meet standards!

Installation and after-sales service matter more than the machine itself

Water purifiers follow the adage ‘three parts purchase, seven parts installation’ – faulty pipework can easily lead to leaks. Prioritise brands with local service centres, ideally offering 24-hour call-out. One user opted for a cheap no-name brand only to find no one could repair it when it broke down, ultimately spending hundreds on a plumber to fix the mess – a costly mistake!

Frequently Asked Questions

Q1: How do I know which water purifier is right for my home?

A: The simplest method is to purchase a TDS pen (costing a few dozen yuan) for testing:

TDS value < 50: Water quality is good; an ultrafiltration unit suffices.

50 ≤ TDS value ≤ 200: Directly opt for a reverse osmosis (RO) unit.

TDS value > 200: An RO unit is mandatory; no other option is viable. Alternatively, contact your local water company to request a complimentary water quality report.

Q2: How often should filter cartridges be replaced? What happens if you forget?

A: Refer to this schedule:

PP cotton: 3-6 months;

Activated carbon: 6-12 months;

RO membrane / ultrafiltration membrane: 2–3 years. If neglected, the filter transforms from a ‘purifier’ into a ‘contamination source’, producing water dirtier than tap water. Long-term consumption may cause stomach upset. Opt for newer models with filter replacement reminders.

Q3: Is a higher waste water ratio better? Can the waste water be reused?

A: Not necessarily! A waste water ratio exceeding 3:1 may compromise filtration efficiency, while 2:1 offers the best value. The waste water produced during filtration can be collected for flushing toilets or watering plants. Some customers do this, saving 30% on their monthly water bill – both eco-friendly and economical!