According to homeopathy, under which circumstances does hom. medicine stop working?

So, I have a substance. I dilute that substance in water. The water mimics that substance with its water-memory and passes this pattern on to a larger volume of water...

Except... What happens if I dump homeopathic medicine into the ocean?
(For example, via a toilet? For example, after passing that medicine through an organism?)

Won't that transform all of the ocean-water into homeopathic medicine?
What kind of homeopathic medicine?
What happens if several homeopathic medicines get dumped into the same volume of water?



Example:
Let's take 100 ml homeopathic medicine of a commercially available D24-dilution.
We dump that into the ocean.
The ocean has a volume of roughly 1.33x10^9 km^3. Let's round it down to 10^9 km^9.
That's 10^18 m^3, that's 10^21 liters.
(10^-1)*(10^-21)*(10^-24) = 10^-46
The ocean is now a homeopathic medicine of a D46-dilution.
Which means, all of the oceans on planet Earth are now a homeopathic medicine of medium strength.




So why should I buy homeopathic medicine when I can just take a sip of sea-water free-of-charge?