A further 12,000 people have chlorine-free water.
Chlorine treatment has stopped at a further three pump stations around the city – Hills, Grampian and Lake Terrace.
Hills supplies 9000 people, while Lake Terrace and Grampian supply about 1500 people each.
The city council isolated the below ground well heads, so unchlorinated water can be supplied from the secure above ground well heads.
Nine pump stations around the city are not being treated with chlorine. By the end of the month, a quarter of the city’s water will be without chlorine.
City council water supply improvements manager Helen Beaumont said it would only be possible to keep these stations chlorine-free during low water demand – such as winter.
She said if residents did not cut back water use in summer, chlorine would have to be used.
Half the city may have chlorinated water for longer than the initial 12-month estimate. A city council staff report revealed making wells secure at 17 pump stations is impossible within the 12 months.