7 Domestic Wastewater Quality Standard Parameters That Must Be Met Before Discharge into the Environment

Domestic wastewater (wastewater from households, apartments, offices, hotels, restaurants, mosques, schools, etc.) must not be discharged carelessly. If not properly treated, it can pollute rivers, lakes, or drainage systems, causing fish kills, human diseases, and ecosystem damage.

In Indonesia, domestic wastewater quality standards are regulated by the government to ensure safe discharge. The primary regulation used to be Minister of Environment and Forestry Regulation No. P.68 of 2016 on Domestic Wastewater Quality Standards. However, as of 2025, it has been updated through Minister of Environment Regulation No. 11 of 2025, which replaces it, including additional treatment technology standards and adjustments for small-scale systems (≤3 m³/day without requiring a specific Technical Approval).

Below are the 7 main parameters most frequently monitored (based on the 2016 standard, which remains a key reference in many cases, with potential tightening under the new regulation):

1. pH (Acidity Level) Safe range: 6 - 9 Explanation: Wastewater must not be too acidic (9). Extreme pH levels can corrode pipes, irritate skin, and disrupt fish and aquatic microorganisms. Common sources: soap, detergents, and decomposition processes.
2. BOD (Biochemical Oxygen Demand) Maximum limit: 30 mg/L Explanation: BOD measures the amount of oxygen required by bacteria to break down organic matter (food waste, human waste). High BOD depletes oxygen in rivers → mass fish deaths (hypoxia). This is a key parameter for assessing organic pollution.
3. COD (Chemical Oxygen Demand) Maximum limit: 100 mg/L Explanation: Similar to BOD, but COD measures oxygen needed for chemical oxidation of all compounds (organic + inorganic). COD is faster to measure and often higher than BOD. High COD also reduces dissolved oxygen in water bodies.
4. Oil and Grease Maximum limit: 5 mg/L (some older references mention 10 mg/L, but 5 mg/L is the common domestic standard) Explanation: Oil and grease float and form a layer that blocks sunlight from entering the water. As a result, algae and aquatic plants struggle to photosynthesize → oxygen production decreases, ecosystems are disrupted, and unpleasant odors develop.
5. Ammonia (NH₃ or NH₃-N) Maximum limit: 10 mg/L Explanation: Ammonia originates from urine, feces, fertilizers, or cleaning agents. High levels are highly toxic to fish and aquatic life (damaging gills) and can convert into harmful nitrite/nitrate. It must be controlled to prevent nutrient overload (eutrophication).
6. Total Coliform (or Fecal Coliform) Maximum limit: 3,000 per 100 mL Explanation: Coliform bacteria indicate fecal contamination (including E. coli). If exceeding limits, the water poses a high risk of spreading diseases such as diarrhea, typhoid, and cholera. This is one of the most critical public health parameters.
7. TSS (Total Suspended Solids) Maximum limit: 30 mg/L Explanation: Suspended particles (sludge, organic residues) that float or settle. High TSS makes water turbid, blocks sunlight, reduces photosynthesis, and covers habitats of bottom-dwelling organisms.

Read Also: How to Effectively Remove Coliform Bacteria from Water

Why Must These Standards Be Met?

• Protect human health from pathogens and toxins.
• Maintain water quality of rivers and lakes for irrigation, fisheries, and recreation.
• Prevent government sanctions (fines, operational shutdowns).
• Support environmental sustainability in Indonesia, where many rivers are already polluted.

How to Comply with the Standards

• Install an independent WWTP/STP (Wastewater Treatment Plant) for apartments, housing complexes, hotels, etc.
• Use technologies such as MBBR, SBR, Anaerobic-Aerobic systems, or constructed wetlands.
• Conduct routine laboratory testing at accredited labs.
• For small-scale systems (