The water business is planning a record £2.3bn investment over the next five years.
Work for the latest framework to come out to tender has been split into six panels of contractors covering major and minor works for the three main categories.
Minor works will be divided across four regions with around three firms appointed to each region. Up to six firms could be appointed for the three national major works categories.
The AMP7 framework will run for five years with options to extend for up to three extra years and covers Wales and parts of Herefordshire and Deeside.
Expressions of interest need to be returned by 4 September. Click for the procurement portal.