The wastewater or sewage produced by enterprises or sewage systems shall be collected through ditches, pipes, or containers within the work environment, and shall not be mixed and collected with rainwater. The preceding sentence is not applicable to runoff wastewater.
Any existing enterprises or sewage systems that are not capable of achieving the goal specified in the preceding paragraph due to difficulties in engineering technique may submit evidence and conduct mixed collection after the competent authority gives its approval, provided that the enterprises or sewage systems have facilities available to prevent direct discharge of mixed wastewater or sewage.

Where the runoff wastewater of an enterprise or sewage system storing or staking the following substances contains such substances or their components, the runoff wastewater shall be collected and treated:
I. Sludge produced during treatment of wastewater or sewage.
II. Coal cinder, coal ash, fly ash, slag, or bottom ash.
III. Raw materials, materials, scraps, products, or by-products that, when washed out by rainwater, may dissolve into or produce substances harmful to the health as announced under this Act.
IV. Hazardous industrial waste.
V. Waste light sources, waste dry batteries, waste pesticide containers, waste containers for special environmental agent, waste lead acid batteries, waste lubricant, waste motorized vehicles, and recycled materials or derivative waste produced during the disposal process.

Enterprises operating in the mining industry, earth and stone extracting industry, earth and stone processing industry, cement industry, earth and stone staking/disposing station, and at the construction site shall set up facilities that are capable of keeping off, blocking and channeling the rain on the excavation surface or stacking station. However, this shall not apply if setting up the facilities to keep off or block the rain is difficult and the competent authority gives its approval.
Enterprises operating in the cement industry referred to in the preceding paragraph means the enterprises that blend the cement, concrete aggregate, admixture, and water thoroughly and transport the mixture to the construction site for grouting.
The enterprises referred to in Paragraph 1 shall set up a grit chamber to collect and treat the initial rainfall and the wastewater produced from car wash platforms; the grit chamber shall meet the following requirements:
I. The total design capacity shall be equal to or greater than the total area of the construction site or workplace multiplied by 0.025 meters.
II. When it is not raining, the distance from the highest water surface to the top of the chamber shall be greater than one-half of its depth.
III. Water impermeable material shall be used.
The facilities for keeping off, blocking, and channeling rainwater as well as the grit chamber shall be maintained and the grit shall be cleaned away on a regular basis; the time at which the maintenance and cleaning are conducted and the method for such measures shall be recorded and the record shall be retained as a reference for three years.
Where any enterprises referred to in Paragraph 1 take the measures specified in Paragraph 1 and Paragraph 3 as approved by the Issuing Authority, their runoff wastewater may be discharged from the approved runoff wastewater discharge point after being treated in the grit chamber.
Where the rainfall is greater than the total design capacity of the grit chamber specified in Paragraph 3, Subparagraph 1, the part of the runoff wastewater whose volume exceeds the total design capacity may be rerouted for discharge.
The domestic sewage produced from the offices and staff dormitories of the enterprises referred to in Paragraph 1 shall be collected and treated appropriately.

Before proceeding to work at construction sites, the parties concerned shall present a plan for the reduction of pollutants from runoff wastewater (hereinafter referred to as “Reduction Plan”) to the competent authority of the municipality or county (city) for approval, and proceed as approved.
The Reduction Plan shall contain the following requirements:
1. Basic information;
2. The measures for the mitigation of pollution as mentioned in the previous article and the engineering plan; and
3. The photocopy of the certification documents issued by the competent authority.
If any of the following occurs to the Reduction Plan, the construction site concerned shall propose the change in the Reduction Plan to the competent authority of the municipality or county (city) for approval by designated deadline and proceed as approved:
1. Any change in the particulars specified in Subparagraph 1 or 3 of the previous paragraph shall be proposed to the competent authority within 30 days from the day after the change. For changes requiring the approval of the competent authority, proceed to the change within 30 days after approval.
2. Change in the particulars as specified in Subparagraph 2 of the previous paragraph shall be proposed to the competent authority before proceeding to change.
3. If there is a concern of the competent authority that the Reduction Plan is insufficient for the protection of the water body after reviewing the plan and pollution is still possible, the construction site concerned will be ordered to take corrective action by designated deadline and shall accomplish the corrective action for improvement by the deadline.
The Reduction Plan for construction sites shall be processed online via the Internet from the date designated by the competent authority.

Enterprises and sewage system other than those specified in Articles 9 and 11 shall take measures to reduce runoff wastewater pollution (hereinafter referred to as the “Reduction Measures”) in accordance with the property of the pollution. Where the Reduction Measures are changed or the competent authority finds they are not appropriate to maintain the quality of the water body and pollution may occur as a result, improvement measures shall be submitted before the change or within the time frame specified by the competent authority, and implemented accordingly after they are reviewed and approved.
Where enterprises and sewage systems take the Reduction Measures pursuant to the preceding paragraph but the quality of the runoff wastewater does not meet the effluent standard, and the municipality or county (city) competent authority finds it may pollute the quality of a water body, the runoff wastewater must be collected and treated.
For the enterprises and sewage systems that shall collect and treat runoff wastewater according to the preceding paragraph and Article 8, the volume of the runoff wastewater to be collected and treated shall be permitted, reviewed and approved on a case-by-case basis. Rerouted discharge is only allowed when the rainfall is greater than the volume of the runoff wastewater to be collected and treated.
For the enterprises and sewage systems referred to in the preceding paragraph, the available capacity of the runoff wastewater collection facilities shall reach the approved and required collection and treatment capacity five days after it stops raining.