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Input:
Question: Does debris get caught in the dirty water tank, or does it clean out easily?
Document: You have to get it EXACTLY lined up in order to get a tight seal and make it work.It does not do a great job of pulling the cleaning solution back out. Only about 50% of the water was returned to the dirty canister. My heavy upright cleaner gets 75% to 80% back.Cleaning out the dirty water tank is a time consuming.
I would not attempt a major carpet cleaning with it.The cleanup was easy. If you have pets or the carpeting was quite dirty, just make sure you clean the 40N7 immediately after use in running water because once the debris dries you will have extreme difficulty removing it.For the cost and if you don't expect it to do more than it is capable of doing, I think buying the Bissell 40N7 is a good deal.
This carpet cleaner is compact and lightweight, so it worked great for my rugs, but I wouldn't suggest doing an entirely carpeted room with it since it is rather small. I wasn't sure how well it would work on Berber, but seeing the water in the tank told me it was cleaning it fairly well (and that my rug was certainly overdo for a shampoo). After I was finished cleaning I took the dirty tank to clean it out, and that was when I became disappointed.
Pros:This machine is lighter than any other upright carpet cleaner I have tested or owned.Easy to fill solution bottle.Easy to remove base from the cleaner.Quick to get out to spot clean.Also quieter than any other carpet cleaner I have used, with no annoying whine.Did noticeably clean the carpet, the water sucked back in was dirty.Has REALLY big back wheels, which make it easy to maneuver.Handle slides down for storage.
The only down side is you use the same container to rinse, so you have to essentially wash the carpet twice, once to wash, then fill the tank with clean water, and go over it again to rinse. This is not too bad for me because my place is pretty small. If you have large rooms it is more convenient  to get the Hoover model that has both wash and rinse in two separate containers, so you just push a button to rinse.
It just leaves gross wet dog hair clumps all over the rug. Also, there seem to be some design flaws. It was just about impossible to screw it together, and when the clean water tank starts to get close to empty, you have to have the handle straight up to get the water to come out, which is really awkward.Overall, it's fine if you just want a cheap cleaner to do a decent job getting dirt out of the carpet.
First, it's very easy to use. You mix a cleaning solution with warm tap water in the top tank. Then plug it in and roll it around as you would a vacuum. There is a trigger in the handle which releases the cleaning liquid into the carpet. Release the trigger to vacuum the water and the dirt it picks up back into the machine. The unit itself is about the same size as our upright vacuum cleaner and light enough to easily carry it up and down the stairs.
Does a good job  and lets you see how much dirt was in the carpet, but...water sloshes out of the dirty water tank (on to the carpet it's just cleaned!) when the tank is above half full. Design deficiency??? Without out this issue, I'd have given it five stars.
Both work pretty well for this, despite being small. The Bissell, being smaller, ran out of liquid more quickly, but before that started spitting foam. This was my fault for not paying attention to how full the dirty water tank was getting.WEIGHTA traditional shampooer is too big to pull out often, but both cleaners are nice and light.
The enclosed carpet cleaner also leaves a fresh smell that lingers for a few days. I recommend the cleaner I use,BISSELL 2X Professional Deep Cleaning Formula, 48 ounces, 78H63I also recommend emptying the dirty water tank BEFORE it gets too full, as the water can splash out and back on the just-cleaned carpet.
Answer: The tank is easy to empty and clean; I've never had a problem with debris left behind.