Not surprised no one knew the answer in Counter-Strike. Full of kids moaning 24/7. Anyways......
Quick answer is that you are suffering from Lag. Happens alot on 56k, can be your ISP's fault or the server which you to choose to play on fault or even YOUR computers fault (unlikey but it happens, check modem drivers and make sure that unneeded background programs are switched off when you play online, esp. Virus checkers)
1 quick fix is to play on servers that are more local to you. For example when I used to play online games I would only play on UK Servers because I'm in the UK.
Another quick fix is to move up to broadband like I did
Would'nt worry too much about that water sound, some people get it, some people dont. I too would get that water sound when playing Team Fortress on a 56k. Just consider it to be an 'alarm' to warn you that you are lagging.