"Napoleon's last Voyages," p. 163.
I found this return in "Admiralty Secret Letters," 1804-16.
Lord Rosebery, in his desire to apologize for our treatment of Napoleon at every point, says ("Nap.: last Phase," p. 64): "They [the exiles] were packed like herrings in a barrel. The 'Northumberland,' it was said, had been arrested on her way back from India in order to convey Napoleon: all the water on board, it was alleged, had also been to India, was discoloured and tainted, as well as short in quantity."—On the contrary, the diary of Glover, in "Last Voyages of Nap.," p. 91, shows that the ship was in the Medway in July, and was fitted out at Portsmouth (where it was usual to keep supplies of water): also (p. 99) that Captain Ross gave up his cabin to the Bertrands, and Glover his to the Montholons: Gourgaud and Las Cases slept in the after cabin until cabins could be built for them. We have already seen (p. 529) that Napoleon was well satisfied with his own room. Water, wine, cattle, and fruit were taken in at Funchal in spite of the storm.
Gourgaud, "Journal," vol. i., pp. 47, 59 (small edition); "Last Voyages of Nap.," p. 198.