Let's face it, the Feds and states have passed so-called "no discharge " laws which are widely unenforceable. And to boot, no law enforcement organizations desire to enforce them. I have cruised the entire NE coast for over 30 years, including some of the most busy harbors, and I have never seen nor heard of from a wide circle of cruising friends, any visible enforcement of the "no discharge" rules, laws, whatever. Not ever, not once. It is totally and completely an honor system. What has happened though is that many newer boats have no way to discharge except through pump-out as their plumbing is so designed.One of the primary considerations when laws are being passed is how they are going to be enforced. It is much simpler and cost effective to prohibit the actual discharge of a tank no matter what its contents may be. There is adequate presumption that the holding tank is to be filled with human waste so it follows that the unauthorized discharge of its contents will be in violation of the law. Something the boat owner as well as the law enforcer can easily understand.