DIY - Carpet Shampoo

http://www.ehow.com/way_5552472_homemade-solution-carpet-shampooer.html

I used this solution with vinegar and baking soda today (no ammonia). Our upstairs hallway has been soaked with water from our bathroom sink which had been leaking, and is now fixed thank goodness! Unfortunately, our predecessors in this place had dogs which used the carpet in that hallway, the girls' room and the living room as their potty. The landlord has since replaced the hallway carpet, but the underlying sub-floor has not been replaced and so still has the stench of the dog pee when the carpet gets wet. Thus, our upstairs smelled atrocious and I couldn't stand it anymore. I mixed up the shampoo, put it in my shampooer and went to town. The water stains are gone, and the upstairs no longer stinks! I am very pleased with the results.

Just a word of caution though. I was reading on other forums that dishsoap will leave a residue on your carpet since it's not being rinsed out, and because of that, dirt will build up sooner. I'd suggest using this only as an emergency alternative, when you can't purchase shampoo that is formulated especially for carpets so the residue and dirt build up doesn't occur. Then when you can afford to, buy the real stuff, and re-clean your carpets. But this is definitely a great alternative in a pinch!