It could be the end of next week before a drinkable water supply is restored to the Fethard region.
Works are continuing to remove all traces of kerosene from the network following a major spillage earlier this month near Mullinahone.
Thousands of homes have been left without potable water since then.
Tipperary County Council expects a deep clean of the treatment plant should be complete before the end of this week.
However Director of Services Sean Keating says tests will then have to be carried out to ensure the water is safe to drink.