All costs and expenses incurred in the preparation, adoption, and approval of an improvement plan shall be paid by the water district out of its general funds, but all such costs and expenses paid or otherwise incurred by the district, upon the approval of the improvement plan, shall be repaid to the general funds of the district out of the proceeds of the first taxes or other revenues collected by the district for carrying out the improvement plan; provided that nothing in this chapter shall authorize punitive assessments to be made against any landowner.