I believe the OP is referring to alcohol hair testing, not urine EtG testing.
Hair Alcohol Testing FAEE is another component that is sometimes tested for in hair testing for alcohol abuse.
Details on FAEE Hair Tests | EthylGlucuronide.net
I have no experience with either, personally and cannot answer if swimming or chlorine would have any affect on either test.
I have done a lot of research on the subject and there seems to be little to no definitive answers that I have found. Interestingly enough, there even exists an International Society committed to Hair Testing Standards!
http://www.soht.org/ The only way I would have any confidence in obtaining a negative hair test for heavy alcohol use is long term abstinence. Aside from having the confidence of passing, it also has a ton of other positive side effects.
We do have an expert in hair testing on this site, maybe he will have some actual professional experience to share.