Residents have had to boil drinking water for three weeks after a parasite discovery at a treatment works.
Some 300,000 homes were initially affected, half of which can now use water as normal.
Parts of Chorley, Preston and South Ribble are the latest to be given the all clear from water firm United Utilities.
It has assessed hundreds of test results after discussions with Public Health England.
Action was taken after the microbial parasite cryptosporidium was found near Preston on 6 August.
Water has been treated with ultra violet (UV) light to kill the parasite, which can cause diarrhoea and cramps.
A petition calling for a parliamentary inquiry into how the bug entered the water supply has been signed by about 12,000 people.
The water firm said it hoped to lift restrictions for people in the Fylde coast area on Wednesday.
Customers can check which areas have had restrictions lifted by visiting the United Utilities website or calling 0800 912 7241.
Advice to boil tap water before drinking it has been lifted in 86,000 more homes in Lancashire.