I’d like to see the documentation supporting that claim.
It’s true that consecrated hosts that have been profaned (let’s say for example, regurgitated) can be soaked in water until they lose their identity as hosts, but the water must still be treated with great care – it cannot be simply dumped down the sewer. I’m sure that’s the same for the Precious Blood but this would be only in seriously grave situations for both species.
But to suggest that the Real Presence evaporates when a greater amount of wine is added to it is not only wrong, it’s pernicious thinking and it’s certainly not a “common teaching.”
So if there is a pint of Precious Blood left over after Mass (gravely wrong in itself) you could just co-mingle it with 17 ounces of fresh wine and the Real Presence vanishes?
I think not.