In 1550, André Thevet, traveller and writer of the Franciscan brotherhood, remarks in his account that only certain cisterns were still filled at the time of the Nile flood. Was this due to the state of the canal or the low water level of the flood?

In 1586, when the English traveller John Evesham visited Alexandria, the canal appeared to be still navigable and correctly performing its role in filling the reservoirs of the town :
"[the water] arrives at the said town [of Alexandria] in such a quantity that vessels of twelve tons ply this water which fills the vaults, the cisterns and the wells in the said town with a very good water, and which stays good until the following year…"

But in 1701, an anonymous Frenchman from the banks of the Garonne, as he describes himself, writes of the old town of Alexandria as completely ruined and says this of the canal :
"The merchants do not go looking for purchases at Alexandria, rather they receive the produce sent to them from Great Cairo and from Rosetta. In other times there was a canal on which were transported goods from this latter town to Lake Mareotis, and from the lake another connected with the old port… Neither one is usable any longer. The barbarians have left the one from Rosetta to fill in… in such a fashion that it can only be partly used when the Nile is high…"

In 1819, Mohamed Ali restored the canal. To do this he was obliged to extend it some 50 kilometres to the most westerly branch of the Nile, that of Rosetta. Charles Blanc, invited to the opening of the Suez Canal in 1869 by the Khedive, wrote:
"This canal has given Alexandria wealth, activity and life."

From the canal to Alexandria the water was channelled through underground aqueducts. Since the Nile water carried a heavy silt, it must be supposed that a filtration system existed before the water even reached the town. No trace of such a system has yet been found, however, two writers at the beginning of the 15th century mention a grill situated by the canal at the point of departure of the channels or aqueducts. This could be a description of a filter holding back some of the impurities before the water entered into the narrower underground aqueducts of the town as can be seen, for example, in the main water tower of Pompeii. The account of Ghillebert de Lannoy (1422) explains:
"And to the south-west, at one mile next to the abovementioned river, a grill of iron, where the channels begin, by which the water comes to the town…"

Another filtration system is presented by Father Vansleb in 1672:
"It should however be known that its opening, whatever the height of the canal, is almost two thirds walled up from bottom to top; in such a way that there is only a small opening, by which the waters of the Calitz [canal] enter, as through a small window. But because the waters of the first three days [of the flood] are very dirty, and the cisterns would soon be filled with impurities if one let the water flow freely during that time, to avoid this inconvenience those who have the duty to bring water to the town block up the hole of this channel and leave it thus for three days; after which they go the mouth of the canal accompanied by a crowd of people to open the channel and let the water enter until the cisterns are filled. The day of this opening is a day of great rejoicing for all the town."