They are also inspected regularly, but no virus has been found.
The border is agreed to be regularly inspected every 25 years.
By law, some types of machinery must be inspected regularly.
A commission spokeswoman said the water is regularly inspected and no problems have been found.
He said the agency regularly inspected its walls and had not found serious problems elsewhere.
Laws had to be enforced, as mine were regularly inspected.
Displayed items need to be inspected regularly for evidence of damage or change.
The plants are inspected regularly for insect damage and disease.
When it became clear that the ferry would be inspected regularly, the North suspended the service.
Each farm is regularly inspected, at the farmer's expense, by both local and national authorities.