Noonsite.com contains this passage
"All yachts should be fitted with either holding tanks
to contain sewage for discharge in waters outside the outer reef edge or have U.S. Coast Guard-approved marine
sanitation devices aboard. However, wherever possible, onshore sanitation facilities should be utilized. The discharge overboard
of sewage, or any other pollutant within the 12 mile Bermuda
Territorial Limit, is an offence, and offenders will be prosecuted."
Consider a camping style chemical toilet for your time in Bermuda. Or, you could possibly install one of the new composting toilets.