On my 9 month tour [as a coffee addict]
Just pour boiling water over grounds in a cup. Wait a couple of minutes and stir - THEY ALL SINK!
All you have to do is maybe catch a couple of floating grounds, [usually less than 10], don't agitate it, and stop before you hit the bottom.
I found that when the grounds are exposed at the bottom of the mug a few little bits will float again, simply press your lips against the edge of the mug and sip gently from below the waterline so as not to slurp in the air/groundsontop.
No equipment required!