(1) Where it appears to a sewerage authority that there are reasonable grounds for believing that in respect of any building, any part of the system of drainage is in such a condition as to be prejudicial to health or a nuisance, the Sewerage Authority may cause such inspections to be made, including opening up of grounds or works, after reasonable notice has been given, as may be necessary to establish the true condition of the system of drainage. Where it appears to a Sewerage Authority that there are reasonable grounds for believing that in respect of any building no satisfactory system of drainage exists then the Sewerage Authority may cause such inspections to be made as to establish the system of drainage, if any.