If you need to test the water NOW and can't, I'm guessing that you suspect a buildup of ammonia in the tank. If that's the case, I'd do a large water change. This should help, and can't hurt (unless the tank has been left without a water change for a very long time, in which case a large change could shock them - then it's best to do small daily water changes).
If you're cycling or the tank is experiencing a 'mini cycle' (spike), a large water change should take care of things until you can get a test kit or some strips.