The incident started when four workers at the plant were cleaning the sewer in Meit Kanaa village, Qalyubia governorate, and fell into it, al-Ahram reported Wednesday.
The rest fell in while trying to save the workers.
Health officials in Qalyubia said that all the victims died of suffocation.
Kris and Bruce Jenner divorcing
WHO expects 20,000 Ebola cases within six weeks