Ballymoney water testing continues into second week
Residents of 3,000 properties near Ballymoney are facing into a second week of boiling their drinking water.
Northern Ireland Water introduced the boil water notice last Tuesday when soil got into its distribution system during work to replace pipes.
A spokesman for NI Water said tests on Monday showed a "significantly improving picture".
He added, however, that there continued to be some low-level sample failures.
While more test results are due later on Monday, the boil notice will continue to allow for two full days of clear tests before it can be lifted.
Earlier, Northern Ireland Water's head of quality and compliance, Dymphna Gallagher said: "The problem is taking longer than expected to resolve due mainly to the length and complexity of the local water distribution system; it extends to over 88 km (55 miles) in length and is mainly rural in nature.
"Northern Ireland Water is making every effort to restore the quality of water to the normal high standard as quickly as possible, through additional chlorine dosing and extensive flushing of the local water distribution system."
NI Water has apologised for the inconvenience caused to customers and will continue testing samples until the water quality returns to normal.
It has provided a list of postcodes affected by the problems.
It will notify customers by card as well as through news and other media outlets.