No matter or thing done, and no contract entered into by any local authority or joint board or port sanitary authority, and no matter or thing done by any member of any such authority or by any officer of such authority or other person whomsoever acting under the direction of such authority, shall, if the matter or thing were done or the contract were entered into bona fide for the purpose of executing this Act, subject them or any of them personally to any action liability claim or demand whatsoever; and any expense incurred by any such authority member officer or other person acting as last aforesaid shall be borne and repaid out of the fund or rate applicable by such authority to the general purposes of this Act.