what do you notice the milk smelling like? yeasty? sourish? If it were mine, I'd taste it and notice if there were any bubbles. For a couple months, my kefir did NOT thicken! I posted a while back about it - didn't know if I was doing it right. When I ran out of raw milk and put the grains in pasteurized milk, they turned it very quickly into a thick kefir. Weird. I've never bought kefir from a store so I'd figured my thin kefir was as thick as it gets. Nope. Now I've been using the store milk for my kefir regularly, and it thickens quickly. When I use raw milk I notice a more sour taste that I don't care for. I hate experimenting w/ raw $$$ milk so not sure when I'll try it again.
Anyway, if you notice any change in your milk, I'd say they are still alive and just need time. Maybe they were in water too long?
Have fun w/ your kefir
Hope they start eating and growing!