Tap water in Exeter has been given the all-clear to be drunk again, South West Water has said.
Bowsers had to supply 2,500 homes in the city
Thousands of people in the city were warned not to drink the water after diesel got into supplies last week.
The "do not drink" notice affected 2,500 households in the Pennsylvania, Beacon Heath and Stoke Hill areas.
It was lifted following a flushing exercise and an extensive monitoring programme. Affected customers are to receive £25 compensation.
The 10 litres of fuel got into the supply after a barrel of diesel was mistaken for chlorine at a pump at Marypole Reservoir on Friday afternoon.
South West Water (SWW) said: "The notice has been lifted following a thorough flushing exercise of water through the network and an extensive monitoring programme.
"All results have now been confirmed as satisfactory by the relevant health authorities and national health experts, who have all agreed that the precautionary notice can be lifted."
SWW said customers may notice a slight residual odour when they first started using their supply.
This could continue for several days but was understood by national health experts not to represent any health risk, the company said.
SWW started an inquiry to prevent a repeat of the incident which it blamed on "human error".