Sub-Decree No. 235 on the Management of Drainage System and Wastewater Treatment System.

This Sub-Decree is enacted to improve the management of drainage and wastewater treatment system in term of efficiency, transparency, and accountability to ensure safety, public health, and biodiversity conservation.
The Ministry of Public Works and Transport shall be responsible for manage and enhance the technical management of the drainage and wastewater treatment system operation, and the duties include: Lead the policy-making, strategy, master plan, and drainage development plan and wastewater treatment system; Prepare technical standard on construction, management, operation and maintenance of drainage and wastewater treatment system; Lead the facilitation with concerned ministries/institutions, development partners, and private sectors for the investment in construction of drainage and wastewater treatment system; etc. The Ministry of Environment shall be responsible for political initiative and set up strategies on wastewater management and for monitoring on the wastewater treatment system process and affluent, and the duties incluide: Prepare policy or strategic plan for water pollution management in public water areas due to wastewater disposal; Prepare Discharge Standard into public drainage system and Effluent Standard of treated wastewater from the wastewater treatment plant; etc. Municipal, District, Khan Administrations shall responsible for managing and providing the services of sewerage system within their jurisdiction area with efficiency, transparency, accountability and environmental safeguard.
The Annex 1 of this sub-decree states the Effluent Discharge Standard from business buildings, residential buildings, satellite towns and resorts, or recreation facilities into the sewage system that connected to the centralized wastewater treatment plant. The Annex 2 states the Effluent Discharge Standard from business buildings, residential buildings, satellite towns and tourist sites, or recreation facilities that have passed through the on-site wastewater treatment system into public water areas or into sewage systems before overflowing into the public water areas.
In addition, the Sub-Decree makes provisions for: monitoring and inspection, penalties, etc.