Need help identifying this engine bay noise...

[TiN]

I've been hearing this noise more and more frequently. Sounds like a washing noise; a rhythmic slosh. I assume that it might have something to do with the water pump, but I have no idea as I've never heard a bad one before. Take a listen and let me know what you think:

<iframe width="1280" height="720" src="https://www.youtube.com/embed/CH1oaDWRRYs?rel=0" frameborder="0" allowfullscreen></iframe>