STORMWATER carrying diluted sewage poured into the Tamar several times at the weekend, TasWater North general manager Andrew Beswick reported yesterday.
However, he said sewage traces in the city estuary was still better than the alternative and should not concern the public.
The Margaret Street pump station normally pumps sewage into the rising main, which is carried for treatment at Ti Tree Bend.
Mr Beswick said this action changed during heavy rainfall when stormwater entered the system, as a result of Launceston's combined sewerage and stormwater infrastructure.
He said stormwater, and some sewage, was pumped directly into the river once the volume passed the second of two levels of stormwater pumps, about five metres up the circular well.
``A large proportion of the solids sewage component will still be pumped through to the rising main and some of it, including all the stormwater at that point, is pumping into the river,'' Mr Beswick said.
``There are still solids at the bottom of the well being pumped into the rising main even in a flood event.''
He said the aged combined system was performing as it should.
``The combined system is good in that it ensures flooding does not occur in the CBD and urban areas,'' Mr Beswick said.
``It is better to be going into the pump station and getting to the river, even if there is some highly diluted contamination, vis-a-vis it flooding around in the streets.''