Before the store I got it from closed (without warning!) I would get wood-chip/sawdust litter. It clumped and was flushable. Frankly, I wish I could find it again, because the clay, although scoopable is easier to clean than the non scoopable, does smell more and takes space in the garbage can (don't use a full bag/week though, and no limit here, so that's not the issue).
See if you can find the wood stuff, it's worth it.