I borrowed my sister's carpet shampooer, but needed cleaner. You can buy a bottle of the cleaner that they sell for use with Rug Doctors wherever they rent the shampooers, but that stuff is spendy, and I prefer gentle, non-toxic cleaning alternatives anyway, so I decided to skip the store and see if I could make a comparable, effective, and non-scary alternative. This is the recipe that I cobbled together from several that I came across.
*1 quart hot tap water (not boiling!)
*1/4 cup hydrogen peroxide*
*1 tablespoon white vinegar
That's it! Other recipes suggested maybe adding some dish soap or essential oils to the mix, but I think that soap and oil on/in your carpet leaves a bit of sticky residue behind that can actually make your carpets more likely to grab and hold on to dirt and gunk.
A sample of my results-
A puppy accident that we did not find immediately. It was there long enough to dry completely, but still came up nicely with just a few passes of the shampooer and no pre-treatment.
I took the "after" shot immediately after cleaning, so I expect that the carpet will lighten up further upon drying completely. So far, I'm really pleased with the results.
*A word of caution with regard to the use of hydrogen peroxide - it has the potential to have a bleaching effect if used directly, in too large an amount or on deeply colored fibers that aren't terribly colorfast. Obviously, I'm not worried about my carpet getting too white (that's never gonna happen!), but if you are, test the cleaner on a small, hidden area first, and/or reduce the amount of peroxide in your solution.