On March 6, Clutha District Council issued a drinking water advisory to residents on the North Bruce, South Richardson and Moa Flat water schemes, including the towns of Waihola, Heriot and Kaka Point.
The advisory said levels of aluminium exceeding new drinking water standards of 1mg/litre had been discovered during testing in February.
Clutha Mayor Bryan Cadogan said although no further exceedances had been detected since March 6, the more than 2000 residents affected should remain vigilant.
"The challenges we face with aluminium are ones we take very seriously, and we apologise to the public for any concern caused.
"A lot of work is going on in the background to rectify this matter and, while we appreciate the inconvenience, we ask and thank the public for its continued patience."
A report from the council said intensive sampling continued to take place at water treatment plants, households and within the pipe network.
Although several of the affected schemes had boil water notices in place, those did not relate to aluminium, but to filtration issues and elevated risk of E. coli contamination.
The report also provided further details of the number of aluminium exceedances prior to March 6.
Puerua had 21 exceedances, North Bruce 16, Moa Flat six, and Kaitangata and Waitahuna one each.
None had since experienced any further consumer breaches, although North Bruce had further elevated samples taken from its pipe network, which were being investigated, the report said.
The council reiterated the risk to health was minimal.
"The health advice is that the risk of consuming water from the affected supplies is negligible; no health effects would be expected at these levels of aluminium exposure, even if water was consumed over a period of weeks to months. This includes effects for people with kidney disease, infants and children."
Water tankers remain available to affected residents.
