This is what we email our clients if that ever happens.
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Post Cleaning Ripples on Residential Carpet:
There are a few things that are causing your ripples. First, residential carpet is rarely installed correctly these days. Most installers only use only a "knee-kicker" to install a carpet even though the manufacturer requires that a "power-stretcher" be used which provides a "tighter" installation. Because of this, it is usually is a little loose to begin with. It might look fine to you, and it might lie flat most of the time, but it probably does not have the needed tension. This is contributing to your problem because just a little bit of expansion on your carpet will cause a major change in appearance. The main cause of the problem though is the carpet backing itself. Carpet manufacturers use clay as a filler in the latex backing. When this backing absorbs moisture, it will expand. So, when the clay in the backing is damp, your carpet is actually expanding. This will cause wrinkles or ripples to appear on the surface. If a manufacturer uses more clay than average in the backing, the problem is more noticeable after cleaning.
Most of the time, to remedy this situation, you simply need to let the carpet dry completely. Once it is dry, it should go back to normal. To speed the process, use fans and/or heat to help dry the carpet to lower humidity levels.
If the wrinkles are still present and you are positive the carpet is totally dry, then you will need to contact a carpet installer to come out to properly re-stretch your carpet using a power-stretcher. (this would be at your own expense do to the fact that the carpet was not installed “tight” enough in the first place or loosened up over time from usage and wear). Karastan, one of the most respected brands of "high-end" carpets in the world mentions this potential problem in their installation guide that requires "power-stretching" This is a quote from their guide: “All installations must be power stretched. After seaming, the installation must be power stretched in all directions. “This helps prevent buckling or wrinkling and provides greater stability.”