What if the water is acid-treated to bring its pH down to an appropriately low, yeast washing pH?
If one is going to rinse with boiled water, lowing the pH of the rinsing and storage water to around 4.2 is a good start. However, in practice, rinsing is a completely unnecessary step that has the potential to do more harm than good.
Brewers are told that they do not have to worry about pathogens because pathogens do not grow in beer. The reason why pathogens do not grow in beer is because the pH of beer is below the minimum growth pH for pathogens such as Clostridium botulinum, which requires a pH of at least 4.8 in order to grow.
A yeast culture "owns" a batch of wort by shutting out competitors. It rapidly consumes dissolved oxygen, which shuts out aerobic microorganisms. A yeast culture also lowers the pH of the medium from around 5.2 to around 4.2, which shuts out pH sensitive anaerobic microflora. The final defense that a yeast culture mounts is the production of ethanol, which is toxic to microorganisms, including the culture itself.
Replacing green beer with boiled water strips the culture of the force field that it built for itself, which means that the water has to be completely free of wild vegetative cells (and spores that can germinate into vegetative cells) because they will feast on dead yeast cells. Bacteria cells multiply three times faster than yeast cells, which means that a small infection can overtake a larger yeast culture when pitched into fresh wort.