The agency plans to check the water quality once per month and publish results on the Asse website, officials said on Friday.
Kissenbrück, part of the Asse joint community, is not connected to the public water system and is supplied by two local wells. But the source belongs to the same rock formation that is near the former mine now used for nuclear waste storage, BfS said. Some fear that radionuclides from the storage facility could leak into the wells.
Meanwhile, a 46-year-old Asse worker is claiming he has leukemia related to his exposure to radioactivity while on the job. Eckbert Duranowitsch began doing research at Asse in 1987, where he was assured there would be no problems with radioactivity.
“The told us that the radiation was lower up on the surface than down in the mine,” he told news agency DDP on Friday.
Asse officials say it's not possible, but Duranowitsch is calling for justice. The city prosecutor in Braunschweig is investigating his claims.
In mid-January the BfS announced that an Asse storage chamber is damaged and could pose the risk of radioactive leaks.
Damage to a 750-metre deep chamber ceiling might cause debris to fall on the radioactive waste in the former mine, the agency said in a statement. While "no immediate emergency measures are necessary," BfS said they were using concrete to stabilise the chamber entrance "quickly" and "preemptively." Asse has since limited employee access to the area.
Asse operators came under fire in the autumn of 2008 following revelations they failed to alert the government to serious violations and worrying conditions at the site.
German Environment Minister Sigmar Gabriel said in September that the facility has "as many holes as Swiss cheese," adding that it remained unclear who was ultimately to blame for the serious safety violations at the site.