Litter Boxes!

I can definitely relate to your problem. We have one cat and 3 litter boxes (upstairs and down - she's old so we try to make it convenient). The weight is incredible. There were discussions about this during the 2010 Reduce Your Waste Stream Team Challenge. If you click on Blog, you can review those discussions.
There is mention of a "flushable" litter. I haven't tried it but might be worthwhile checking into.
Good luck!
P.S. I forgot how many blogs were on that site; the discussion on cat litter starts on Page 4 with "Hi there,
Waste Busters" and continues on to Page 5 under "Cat Litter Thoughts". Hope that helps!

- Linda Wainstock, Waukesha County Recycling

I was reading about using the eco friendly litters( wheat, pine, and corn based) that are supposed to be compostable. I also found a website telling how to make your own pet waste composter(dogs) but I don't see why you couldn't use it for cats too. Put the clumps into the pet waste composter and put the rest of the litter in the regular compost.
http://www.plantea.com/dog-waste-compost.htm

We recently got a kitten and I knew that I wasn't going to be adding all that weight to my garbage. Being an avid composter I decided I would figure out a way to compost it. A few friends tipped me on using pine pellets as kitty litter instead of a clay based kitty litter. Seems to be working just as well and is significantly cheaper. I actually noticed a product called "feline pellets" at a pet store recently, but was almost 3 times the cost of pine pellets at the hardware store. I have set up a separate compost bin that I add the litter to then cover with straw. I'm even adding some other yard materials to that bin every now and again. More water will most likely be needed to help break up the pine pellets but I can do that.

This compost will be strictly for landscaping, not for my vegetable garden, which is why I set them up in two separate bins.

Not a tested method but so far so good :)

-Angie Lemar, Associated Recyclers of Wisconsin (AROW)