The Canadian firm received the same warning as other residents when officials said on Monday that the water supply was being cut off for four days for maintenance work.
Authorities then revealed that the move was related to the explosion of a chemicals plant at Jilin city on 13 November, which threatens to pollute the water supply in neighbouring regions, including Harbin.
The official China Daily newspaper cited a local official as saying that the pollution has entered the Songhua river.
The McCain plant, opened in September, makes 7.5 tons of chips, also known as French fries, each hour, and is expected to supply other Asian markets in the future.
A spokeswoman for the firm told AP-Foodtechnology.com: "We'll monitor it on a daily basis. We're not sure how long it will last."
Anheuser-Busch, the US brewery that is also based in the area after it acquired Harbin Brewery last year, said yesterday that it had not been significantly affected by the lack of water.