There are 2 basic methods of carpets cleaning, Dry and Wet. The dry method uses encapsulation, which works as follows - the carpet is vacuumed to remove loose soil, a pre-spray is applied to help loosen deep soil, then the encapsulation powder is liberally sprinkled on (looks a bit like sawdust), brushed in and left for 20 minutes.
During this time the powder attracts the dirt, which is then vacuumed up. The wet method starts the same, but instead of sprinkling the powder on, a hot detergent solution is applied to the carpet and sucked up a vacuum hose. This leaves the carpet touch damp, and will usually be dry within 8 - 12 hours depending on carpet type and weather conditions.The chemicals used in both methods are specifically designed for the job and are not 'harsh'. Not using chemicals will result in a poor quality job and will probably mean you will have to call someone out to re-do the job.
My personal opinion is that the wet (hot water extraction) method is the best, and if drying time is critical, any good cleaner should have a powerful floor fan that will dramatically speed up drying time. Search for companies on Google, check their feedback ratings and when you call them, if they can book you in very quickly, they may not be good enough to be busy. It is better to wait a few weeks and get a good company than get someone who can come out immediately.
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