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IS 17268:2019 is the Indian Standard (BIS) for blackwater treatment systems - code of practice. This standard provides a code of practice for the planning, design, installation, operation, and maintenance of blackwater treatment systems. It outlines various technologies and sets performance requirements for treated effluent to ensure it is safe for non-potable reuse applications like toilet flushing and landscape irrigation, promoting water sustainability.
Provides guidelines for the design, installation, operation, and maintenance of blackwater treatment systems for reuse or safe disposal.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! A clear distinction must be made between blackwater (toilet waste) and greywater (from sinks, showers); this code is exclusively for blackwater.
! The success of a blackwater treatment system is critically dependent on consistent and proper Operation & Maintenance (O&M). Under-resourcing O&M is a common cause of system failure.
! A dual plumbing (pipe) system is mandatory to keep treated non-potable water completely separate from the fresh potable water supply, preventing any risk of cross-contamination.
EN 12566-3:2005+A2:2013CEN (European Committee for Standardization), European Union
HighCurrent
Small wastewater treatment systems for up to 50 PT — Part 3: Packaged and/or site assembled domestic wastewater treatment plants
Specifies requirements and test methods for packaged domestic wastewater plants, mirroring the IS code's focus on prefabricated systems.
ISO 30500:2018ISO (International Organization for Standardization), International
HighCurrent
Non-sewered sanitation systems — Prefabricated integrated treatment units — General safety and performance requirements for design and testing
Covers prefabricated, non-sewered units with performance requirements for reuse, aligning closely with the IS code's objectives.
NSF/ANSI 40-2021NSF International / ANSI, USA
MediumCurrent
Residential Wastewater Treatment Systems
Focuses on performance testing and certification of residential-scale systems, but typically for combined wastewater (greywater + blackwater).
ISO 24521:2016ISO (International Organization for Standardization), International
LowCurrent
Activities relating to drinking water and wastewater services — Guidelines for the management of basic on-site domestic wastewater services
Provides management guidelines for on-site services rather than technical design specs, but overlaps on operational and maintenance principles.
Key Differences
≠IS 17268 is specifically for 'blackwater', whereas most international equivalents like EN 12566 and NSF/ANSI 40 are designed and tested for combined 'domestic wastewater' (blackwater and greywater).
≠The Indian standard specifies design influent characteristics (e.g., BOD 350-450 mg/L) that are typical for Indian conditions with lower per capita water consumption, resulting in more concentrated wastewater than assumed in many European or North American standards.
≠IS 17268 explicitly defines effluent quality for specific reuse purposes common in India, such as toilet flushing and horticulture. International standards like EN 12566 focus more on performance for safe discharge to the environment, leaving specific reuse criteria to national regulations.
≠The regulatory context differs; IS 17268 is a 'Code of Practice' for implementation within India, while EN 12566 is a harmonized standard tied to product certification (CE marking) for market access in the EU.
Key Similarities
≈All standards share a primary focus on packaged, prefabricated, or site-assembled systems for decentralized applications, as opposed to large, civil-engineered municipal plants.
≈They all adopt a performance-based approach, defining required effluent quality (e.g., limits on BOD, TSS) that a system must achieve under specified conditions.
≈The core parameters for assessing treatment performance are consistent across the standards, including Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), and often nutrients like nitrogen.
≈All include requirements covering the full lifecycle, including guidelines or mandates for proper installation, operation, and maintenance to ensure sustained performance.
Parameter Comparison
Parameter
IS Value
International
Source
Effluent BOD₅ (for reuse/high quality)
< 10 mg/L
< 10 mg/L (Class A Effluent)
ISO 30500:2018
Effluent Total Suspended Solids (TSS)
< 10 mg/L
≤ 30 mg/L (30-day average for Class I)
NSF/ANSI 40-2021
Pathogen Indicator (for reuse)
< 100 MPN/100 ml (Fecal Coliform)
< 250 CFU/100 ml (E. coli, Class A)
ISO 30500:2018
Effluent pH Range
6.5 - 8.5
6.0 - 9.0
NSF/ANSI 40-2021
Turbidity (for reuse)
< 2 NTU
< 5 NTU (Class A Effluent)
ISO 30500:2018
Design Influent BOD₅ Concentration
350 - 450 mg/L
Varies by test protocol; typically 150-300 mg/L for residential systems.
NSF/ANSI 40-2021
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Target pH for reuse6.5 to 8.5
Max BOD for toilet flushing (mg/L)< 10
Max Turbidity for toilet flushing (NTU)< 2
Max Total Suspended Solids (TSS) for flushing (mg/L)< 10
Max Faecal Coliform for flushing/irrigation (MPN/100ml)< 100
Minimum Residual Chlorine for disinfection (mg/L)0.5
Tables & Referenced Sections
Key Tables
Table 1 - Typical Characteristics of Blackwater
Table 3 - Recommended Treated Blackwater Quality for Reuse Applications
Annex A - Comparison of Various Treatment Technologies
Key Clauses
Clause 5 - Planning and Design Considerations
Clause 6 - Treatment Technologies
Clause 8 - Performance Requirements of Treated Blackwater
It is wastewater discharged from toilets, urinals, and bidets, containing human excreta (faeces and urine). (Clause 3.1)
What are the primary applications for treated blackwater?+
The main reuse applications are toilet/urinal flushing and subsurface or drip irrigation for landscaping. (Clause 8, Table 3)
Does this code recommend a specific treatment technology?+
No, it does not mandate a single technology. It provides guidance on various options like SBR, MBR, and MBBR, allowing the designer to choose based on site conditions, cost, and required performance. (Clause 6 & Annex A)
What is the effluent standard for BOD for reuse in toilet flushing?+
The Biochemical Oxygen Demand (BOD) should be less than 10 mg/L. (Table 3)