Section 29. Preparation of plans and supervision of construction by registered sanitary engineers required. —

It shall be unlawful for any person or firm to order or otherwise cause the construction, erection, installation or alteration of any sanitary engineering equipment, machinery or process for any sanitary engineering work, project or plant, the cost of which exceeds five thousand pesos, unless the designs, plans, layouts, and/or specifications have been prepared under the responsible charge of, signed and sealed by a registered sanitary engineer, and unless the construction, erection, installation, and/or alteration thereof are executed under the responsible charge and direct supervision of a registered sanitary engineer.