Apparently my arguments have stirred up the group intollerance.
If you agree I would restart the MSD discussion in a different thread and
reformulate it.
I am really interested...

You aven't got my point: disregarding the legal point or even the
chemical
pollution, the soap can be safe and not chemically polluttant (maybe...)
But you can guarantee that the oil (only to remain with your example...)
that the soap as removed is also safe and not polluttant?

No...soap or detergent is safe, and so is anything that goes down a sink
or shower drain. But there is no soap, detergent or other cleaning
product that can transform a pollutant--say, oil in a bilge--into an
environmentally friendly product. Which is why it's such a mystery to me
that boat owners are so concerned about organic matter in gray water or
treated toilet waste, but give no thought at all to what their bilge
pumps are discharging.

I am interested only in small sailboat, i am building one 26' catamaran.
The only oil that you can extract from my bilge will be olive oil... :-)

And even if it is safe, do you tink that a place full of soap bubbles
and
oil and watermelon seeds floating around is nice place where to send the
boys to swim?

Don't confuse galley WATER with galley waste (garbage)--which is what
watermelon seeds are. As for any oils (cooking or body), they're
emulsified by detergents and soaps...and most of those are very low suds
these days. You're far more likely to see suds and bubbles around a boat
being washed than from any sink drains.

I have trouble with the language, I don't explain clearly my mind.
The watermellon seed is only one example of what can transform a clean
peacefull place into something unpleasant, disgusting...
I try with another example: if the bottom is mud, a small movement transform
the water from cristal clear to something dark and unpleasant... it is
safe, but I don't like it.
In the same way the boat discarge: head, galley, ad bilge water can be safe,
but doubtless aren't "cristal clear"...


If you're really sincere about protecting the ocean environment,
concentrate your efforts on keeping oil and grease out of the bilges
instead of worrying about what goes down a drain.

I agree: my engine is wind.
But sometimes the actions have a "flag" value: over my roof I have
photovoltaic panels, I do know that the energy balance (amount of energy
used to produce the cell/ amount of energy generated in the life) of
photovoltaic cells is largely debatable and my photovoltaic panels don't
change my country energy balance... But I have put my money there because I
want a greater attention to this type of problems.

Paolo