Up to 18 contractors could be selected for the four-year deal , which is being split up into three packages to cover North Wales, the South East and South West.
The water company hopes to select six companies for each region.
Works will cover general maintenance and civil engineering, including sewer modernisation and gravity pipeline work.
Interested firms can apply for all areas and can apply for further information from Martyn Wordsworth on tel: 01443452300 or at firstname.lastname@example.org by 9 February.
Lot 1:Conway, Denbighshire, Flintshire Gwynedd, Isle of Anglesey, North Powys and Wrexham.
Lot 2: Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Merthyr Tydfil, Monmouthshire, Newport, Rhondda Cynon Taff, South Powys, Torfaen, the Vale of Glamorgan and parts of Hereford
Lot 3:Carmarthenshire, Ceredigion, Neath Port Talbot, Pembrokeshire and Swansea
Welsh Water is also currently assessing bids for a £156m framework deal covering trunk main cleaning, renewals and meter installation, which has been divided up between North and South Wales.