You can tell a lot when people respond with name calling, unfriendly hostility, and petty smear attempts to distract from facts they'd rather bury. There’s no need for it and this isn’t a children’s playground.
Hot water extraction will always be the best way to clean carpet. As someone who worked as a professional capet cleaner and who has removed carpet I can speak definitively. In fact, hot water extraction is the method recommended by the Carpet & Rug Institute. Let’s also notice that in the videos a real vacuum isn’t used, but rather a stick vacuum for someone who speaks as they know what they’re talking about when cleaning carpet. I also never saw the carpet rolled back showing what the backing looks like comparing the methods. I can tell you I am not going to be cleaning my 2,200 sq ft of carpet with a rag or any dry form of carpet “cleaning” product. Hot water extraction is the key. Then you use air movers to dry it thoroughly.
Before I get onto the science, firstly, I’ll just say that criticising for reasons as trivial as using a stick vac makes no sense in the context of the discussion in the videos and just comes across as misguided and missing key knowledge. The best stick vacs on the market are measured to achieve the highest levels of cleaning performance and it's no longer a debate since it's easily quantifiable. Secondly, the CRI holds no credibility with me. They’re industry-owned, goal-focused, and their output is not peer-reviewed. There’s evidence of bias, unconvincing testing, and it’s not always science-based or consistent with the formal industry standards. They should be seen as lightly informative at best, not authoritative—sadly this is rarely the case, but this failure of interpretation is itself revealing.
Onto the science. I understand why businesses whose trade is in carpet cleaning choose to use hot water extraction—it's quick and fairly effective in ‘appearance cleaning’ only. But there are serious drawbacks that are scientifically well established, and I’ll talk you through these seeing as you won’t otherwise find the knowledge unsuppressed on closed social media or lay chat forums. You can fact-check all this yourselves, so I encourage you to.
There are scientific studies
that have quantified the cleaning effectiveness of hot water extraction. These studies conclude that it is very effective at cleaning the surface, but considerably less effective deeper in the pile, leaving behind a lot of allergens at depth. This is unsurprising, since
other scientific studies have shown wet extraction is no better than simply dry vacuuming at removing allergens, which both tend to change the distribution more than remove the reservoir at depth. And it’s clear why that is physically from an understanding of
air dynamics as a function of depth in pile. Worse,
other studies have shown that growth of microbiological nasties increases at depth in pile over time once wetted by such cleaning methods, leaving it dirtier than before it was cleaned. Alternative methods that do not use water have been shown in a number of studies to avoid all these problems and achieve similar surface cleaning performance and better removal of allergens deeper down.
This study, for example, found that microsponges were very effective at reducing microbiological growth and mites at depth. This is consistent with research studies presented at the Sixth International Conference on Indoor Air Quality and the Environment – Helsinki, Finland, and Seventh International Conference on Indoor Air Quality and the Environment in Nagoya, Japan, showing just a single use of microsponge resulted in significant reductions in a range of microbiological nasties. Specifically, reductions in dust mites by 78%, cat allergens (dander, hair and saliva) by 85%, dust mite allergens by 75%, and mould spores by 85% to 94% even in humid environments associated with temperate climates. This method also has low resoiling rate, evidenced
in the first post, since no sticky residue is left behind unlike with evaporating water-based methods using various chemistries. Overall, it achieves comparable surface cleaning to hot water extraction but better allergen removal at depth and reduced resoiling rates.
Such non-water-based methods are also used professionally as well by cleaning businesses, and these were provided
above. The idea that multiple large air dryers are needed after wet extraction simply supports the very problem I’m highlighting.
Ultimately, this post wasn’t about professional cleaning of large areas in commercial settings, in which case you’d use specialist equipment—either hot water extraction with all the drawbacks well understood but little talked about, or CRBs and microsponges as evidenced by some businesses
in the first post. This post was about real-world home spot messes, the flaws with water-based carpet cleaners and why they’re essentially a scam, and cheaper alternative methods which are far more effective. The evidence for all this was provided, again,
in the first post, which I recommend reading.
