Work has officially commenced for phase one of the City of Weyburn's water treatment plant reservoir.

Valves will be shut off at the 16th Street reservoir on tonight around 10 p.m., for work to begin to tie in the new valves to the main distribution line.

This work is continue throughout the night, when demand for water is low, and is anticipated to be complete by 6 a.m. Friday morning.

Water pressure may be low during the night, according to superintendent of the water treatment plant Shabbir Sakrani, but it is to stay around 40 PSI (the Water Security Agency requires pressure to remain above at least 20 PSI).

Sakrani anticipates this to last six to eight hours, depending on the difficulty of the job, as the pipe is around 30 to 40 years old and contains asbestos.

A second reservoir located on First Avenue will be used to feed water to residents tonight. Sakrani said this reservoir can feed up to 1,500 litres per minute, but asks that use of water by residents remain low tonight if possible.