New kittens, and new things to learn. My wife says I shouldn’t flush the scooped excrement and litter, as it will in some way screw up the pipes. The stuff isn’t that big, and the water moves through the sewer pipes at a pretty good clip. What is going to go wrong?
Any cat owners with the Straight Dope on flushing cat nuggets?
Some litters are designed to be flushable, some are not. Clumping litters in particular are often nonflushable. A lot of litters are clay based, so that might screw up sewage treatment plants, and I’m sure they’re not good for septics. I use a litter that says “flushable” on the package, so I flush without worry.
With regular litter, the grains don’t dissolve in water, so it would have the same effect as flushing gravel down your toilet. There does exist, though, flushable clumping litter. The one I use is made from corn (World’s Best Cat Litter, twice the cost of most other clumping litters but well worth it), and when a clump is placed in the toilet it will immediately dissolve into mush that can then be flushed.
To expound on what Cheesecake said, clay will settle in the trap (the “U” bend that keeps sewer smells in the sewer), impeding flow. Won’t block the pipe by itself, but can be bound by other stuff to do so.
Accordingly, look for a flushable litter. Some clump, others don’t. You simply swap out the non-clumping ones more often. FWIW, my housemate and I tried the corn-based litter. Worked reasonably well, but the litter tracked a lot, corn starch especially. Are having better luck with a wheat-based flushable-clumpable called Swheat Scoop, though only two weeks into the experiment. YMMV.
One thing to consider for later on is potty-training. Can’t be done with kittens, but a grown cat can be trained to use the toilet. (I’ve done it.) Some people, though, my housemate for one, aren’t interested in sharing the toilet seat with their critters. Ya’ll will have to make your own decision.
Though there is flushable litter, I still wouldn’t recommend it for septic based systems.
If you’re on a public sewer system, go right ahead! 
I tend to be paranoid about my septic system, repairs are just too expensive to fiddle with flushing. I’m on a whole bunch of land though, and have no issues with finding a place to dump out used (traditional) litter.
Agreed.
It also does things like infect Sea Otters, so it’s not a good idea in any case.
Huh? If you flush cat waste into a municipal sewer system, it gets treated along with the human waste. Or are you saying there’s some particular feline bug that slips through?
Double “huh”? I doubt the remnants of flushed kitty poop coming though the septic systems of us land mammals would specifically affect one specie of marine life. Maybe all the sewage we dry-landers generate put together would affect the ocean world, but I’d think cows would be the biggest culprits in terms of offense to the oceans.
Scientists have not yet determined the cause of the deaths, but two culprits are suspected: domoic acid, a natural marine toxin produced by algae during “red tides”; and parasite-ridden cat feces that is either washed into the ocean in storms or carried by kitty litter flushed down the drain.
http://www.seaotters.org/CurrentIssues/index.cfm?DocID=204
One problem California has is that some of their otters are dying from a disease related to people flushing kitty litter down the toilet.
http://www.ktuu.com/CMS/templates/master.asp?articleid=11059&zoneid=4
In 2002, scientists found evidence that the steady drop in the state’s sea otter population can partially be blamed on a parasite found in cat feces – toxoplasma gondii. One possible reason for that: cat owners flushing kitty litter down the toilet, which eventually drains into the sea.
http://www.otterproject.org/site/pp.asp?c=8pIKIYMIG&b=106794
“Kitty Litter” is actually a trademark owned by Edward Lowe Industries for its brand of cat litter.
Interesting, Dr Deth. I note, however, that the science isn’t quite as conclusive as the original comment suggested. That is, cat feces are strongly suspected of contributing to otter deaths, but which ones is unclear. Indeed, as mentioned in your first link, the prevailing view appears to be that run-off from feral cat populations is the prime culprit. To similar effect, see this NOAA article.
Bottom line. If I lived in Monterey and/or had outside cats, I’d stay away from flushable litters, just to err on the side of caution. Since I am neither, I don’t think it’s irresponsible to continue using them. Especially since the alternative, dumping in a landfill, also has ecological implications.