Performance Inspection of Small-Scale Sewage Treatment Facilities

Korea Institute for Water Technology Certification.

Small-Scale Sewage Treatment Facilities

What Is an Individual Sewer System?
Drainage systems, small-scale sewage treatment facilities, and auxiliary facilities installed by a building or facility owner to discharge or treat wastewater generated from the building or facility.
What Is a Small-Scale Sewage Treatment System?

A facility that treats wastewater generated from buildings or installations through sedimentation, decomposition, or similar processes. It is classified as follows:

  1. Septic Tank
    • Outside sewage treatment areas:
      • buildings or facilities with daily wastewater generation ≤ 2㎡
    • Within sewage treatment areas (combined sewer areas only):
      • when installing flush toilets
  2. Sewage Treatment Facililty
    • Outside sewage treatment areas:
      • buildings or facilities with daily wastewater generation > 2㎡
      • when installing flush toilets or facilities generating > 1 ㎡ of wastewater per day in special countermeasure areas or waterfront areas

Inspection Target

Inspection Target
Sewage treatment facilities among small-scale sewage treatment facility products regulated under Article 52 of the Sewerage Act
Inspection Overview
A total of eight samples are collected over six months. If the BOD influent loading is less than 70% of the design value, or if the effluent quality exceeds the standards specified in the application, the applicant is notified of non-compliance.
Inspection Period & Number of Tests
  1. Inspection Period

    The inspection is conducted for six months starting from the date when the BOD influent loading of the installed treatment facility reaches at least 70% of the design value, and must include at least 50 days between December 1 and March 31.

  2. Number of Tests

    Sampling and analysis are conducted once per month, with three samples (morning, noon, evening) collected during the final month. A total of eight sampling and analysis events are performed.

Water Quality Requirements
  1. BOD influent loading: ≥ 70% of design value
  2. Effluent quality: must meet or be below the discharge standards specified in the application
Water Quality Analysis Items
  1. Capacity < 50 ㎥/day: Biochemical Oxygen Demand (BOD), Suspended Solids (SS)
  2. Capacity ≥ 50 ㎥/day: BOD, SS, Total Nitrogen (TN), Total Phosphorus (TP), Total Coliform Count

Fees

Inspection Fees
  1. Facilities < 50 tons: KRW 3,500,200 per unit (incl. VAT)
  2. Facilities ≥ 50 tons: KRW 4,178,900 per unit (incl. VAT)
  • ※ (Basis for Fee Calculation) Regulation on Fees for Material Testing Agencies and Performance/Material Testing of Small-Scale Sewage Treatment Facilities (Ministry of Climate, Energy and Environment Notice No. 2022-226, amended on November 28, 2022)
  • * (Note) For performance inspections of small-scale sewage treatment facilities, factory inspections are not included; therefore, the fees specified in the Notice are applied as-is for each facility. Although the fee components are categorized into testing and analysis costs, direct labor costs, etc., the detailed cost breakdown reflects all expenses incurred over the six-month inspection period. If the facility is determined to be non-compliant, the fees for the remaining inspection rounds are refunded. Accordingly, fees are charged solely based on facility capacity (under 50 tons / 50 tons or more), and the corresponding fee table from the Notice is provided.
Classification Sewage Treatment Facility
(Less than 50 ㎥/day)		 Sewage Treatment Facility
(50 ㎥/day or more)
Actual Performance Inspection Total KRW 3,182,000 KRW 3,799,000
Testing & Analysis Costs BOD KRW 35,900 × 8 tests × 2 samples = KRW 574,400 BOD KRW 35,900 × 8 tests × 2 samples = KRW 574,400
SS KRW 11,300 × 8 tests × 1 sample = KRW 90,400 SS KRW 11,300 × 8 tests × 1 sample = KRW 90,400
- T-N KRW 12,900 × 8 tests × 2 samples = KRW 206,400
- T-P KRW 13,100 × 8 tests × 2 samples = KRW 209,600
- Total coliform KRW 25,100 × 8 tests × 1 sample = KRW 200,800
Direct Labor Cost KRW 199,510 × 2 persons × 3.5 days = KRW 1,396,570 KRW 199,510 × 2 persons × 3.5 days = KRW 1,396,570
Overhead KRW 841,464 KRW 841,464
Travel Expenses KRW 40,000 × 2 persons × 3.5 days = KRW 280,000 KRW 40,000 × 2 persons × 3.5 days = KRW 280,000
Document Review Direct Labor Cost KRW 199,510 × 1 person = KRW 199,510 KRW 199,510 × 1 person = KRW 199,510