Over 13,000 people are affected as a boil water notice has been reissued for the Lough Talt Regional Water Supply scheme, following the detection of cryptosporidium in the treated water coming from the plant.
This affects the towns of Tubbercurry and Ballymote, and a large rural hinterland of south Sligo including the villages of Annagh, Aclare, Curry, Lavagh, Ballinacarrow, Carrowneden, Kilmacteigue and Coolaney.
The boil water notice also affects customers supplied by the Ogham Group Water Scheme, as well as customers in the Cloontia, Doocastle and Quarryfield areas of Co Mayo.
A boil notice was originally issued for the Lough Talt water supply last February, and wasn't lifted until October.
However, the supply has been monitored closely by Irish Water since then, and following the recent detection of cryptospodidium and two cases of illness, a boil notice has again been issued for the Lough Talt water supply.
Consumers are advised to boil water for drinking, preparing salads and uncooked foods, brushing teeth, and making ice.