A severe recent drought and years of neglect means that the pipe system in the city has fallen into disrepair.
The BBC reports that Bulawayo mayor Thaba Moyo said that the lack of water in the sewage pipes had already led to many bursting.
He added that the simultaneous flush would theoretically run water through the pipes and prevent them from becoming blocked in the future.
The first flush took place at 7.30pm local time yesterday (September 24), with a large number of the city's million-strong population believed to have taken part.
The communal flush is now set to take place twice a week, on Mondays and Wednesdays.
The innovative approach to city maintenance has met with a mixed reception from residents, with local Petros Ncube arguing: "Our leaders are a joke... what they should be doing is finding money from donors to buy new sewer pipes."