Where it appears to a local authority that there are reasonable grounds for believing that a sanitary convenience, drain, private sewer or cesspool is in such a condition as to be prejudicial to health or a nuisance, or that a drain or private sewer communicating. . . indirectly with a public sewer is so defective as to admit subsoil water, they may examine its condition, and for that purpose may apply any test, other than a test by water under pressure, and, if they deem it necessary, open the ground.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If on examination the convenience, drain, sewer or cesspool is found to be in proper condition, the authority shall, as soon as possible, reinstate any ground which has been opened by them and make good any damage done by them.