Does decaf coffee count at all toward
 

daily water requirements? I know it might sound like a stretch, but without the caffeine isn't it somewhat countable?

No.
 

Only pure water counts towards your daily water intake - anything else, even plain seltzer water, is considered "in addition to", according to the good doctor. I think it's because, decaf or not, it still contains substances that need to be filtered and processed by your kidneys, whereas pure water is what helps your kidneys process.

I spoke to an Atkins Associate last year re this subject.

Only water, seltzer and some light herbal teas count towards your water intake. But of course, pure water is the best.

Even though Atkins advises that only water counts as water, the vast majority of doctors do include other sources as daily intake: coffee, decaf, milk, juices, sodas, and fruits and vegetables with a high water content.

Because coffee is a diuretic, it's best to count just half of the water intake. I decided to drink 8 glasses of water a day, and any coffee or diet sodas are just extra.

I haven't found anything written by Atkins (I may have missed it somewhere) where he advises people to drink 120+ ounces of water a day, like most Atkins followers suggest.