According to the latest report (2013), just released from the Ministry of Environment, Energy & Climate Change, on the quality assessment of Greek bathing waters, in 94 % of the sampling points you could practically drink it as they have been classified of “excellent quality”. Actually, you would not have any problem enjoying the sea throughout Greece as 99.8 % of the sampling points have been assessed as suitable for swimming, according to the European Directive 2006/7/EC.
The assessment concerns the evaluation of microbiological parameters in more than 2150 sampling points across Greece and the statistical analysis of the results over a 4 year period.
You can find out more about the quality assessment program of the Greek bathing waters at http://www.bathingwaterprofiles.gr/en and the full report for 2013 is availabe at “Bathing Water Quality in Greece”.
Please enjoy them responsibly!