Christchurch's two earthquakes have not had a significant impact on the city's drinking-water aquifers.
The Canterbury Regional Council has tested water quality and found it to be similar to that before the earthquakes.
The council analysed 35 wells around Christchurch, measuring pH levels, dissolved oxygen and salts and minerals among other things.
The regional director of investigations and monitoring, Ken Taylor, says it's pleasing to find the quality hasn't changed.
He says shallow groundwater in some areas may have been contaminated by breaks in wastewater pipes, but there is little risk of bacterial contamination to the deeper aquifers.
