As rapid population and urbanisation in our country have put pressure on our water resources, it is vital to consider sustainable solutions in water and wastewater system, especially to our wastewater treatment plant design. Several studies have shown the importance of having an indicator in both plannings, designing and operating a wastewater treatment plant to help develop a sustainable method in wastewater treatment plants. Therefore, this paper presents a study of crucial sustainable indicators for designing Malaysia’s sewage wastewater treatment plant. This paper focused on three (3) aspects: environment, social and economic, followed by significant data to emphasise sustainable indicators. This study was conducted using a quantitative methodology (survey questionnaire online form) and distributed to wastewater engineers or any groups related to the wastewater treatment plant in Malaysia. The survey conducted showed that most crucial sustainable indicators in sewage WWTPs design were (i) nutrient removal, (ii) worker’s health and safety, (iii) public health and safety, (iv) operational and maintenance costs, (v) energy consumption and (vi) greenhouse gases emissions.