From the beginning of Thammasorn Company Limited in 1991 until now as a manufacturer and distributor of above-ground water storage tanks Underground water storage tank, grease trap tank, wastewater treatment tank, and wastewater treatment system design under the brand name DOS with the objective Conducting business to help alleviate Thailand's environmental problems By doing business in the field of good water and waste water, taking care of and solving water problems completely. There is also a business expansion. to other environmental businesses nearby such as waste management systems, waste incinerators, sorting machines Comprehensive waste management system to cover more services Currently, the company has grown and continuously developed until being trusted by leading project companies in Thailand And has been a part of the success in many projects, both public and private sectors under the concept of Total Water Management, in which all sectors are confident in the highest quality and service. And raised to be a true expert in water management