Bonds issued pursuant to the water and sewer district revenue bond act shall not be a debt of the district and the district shall not be liable thereon, nor shall they be payable out of any funds other than the revenue pledged to the payment thereof. Each bond issued under the water and sewer district revenue bond act shall recite, in substance, that said bond, including interest thereon, is payable solely from the revenue pledged to the payment thereof. Bonds may be issued under the water and sewer district revenue bond act notwithstanding and without regard to any limitation or restriction on the amount or percentage of indebtedness, or of outstanding obligations of a district.