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Addendum in Malaysian Sewerage Industry Guidelines (MSIG) 2025

by | Jul 25, 2025 | Blog

Based on the new guideline published by Suruhanjaya Perkhidmatan Air Negara (SPAN), there are few components that have been added and updated. In this guideline, SPAN implemented risk-based sewerage solution design to meet the specific needs of each region.

New guideline can referred here.

Sewage generation rates

Sewage generation rates refers to the amount of sewage generated per person, per day. In the previous guideline, the sewage generation rate was 225 litres/day. Now, it has been revised to 210 litres/person/day under the updated guideline.

Image 1.1: Previous sewage generation rate from Section 3 Design Guide: 3.3.1 Volumetric Capacity 

Image 1.2: New sewage generation rate from Chapter 2: Section 2.2, Page 2-29

Peak flow factor

Peak flow factor is one of the significant changes from the previous guideline. The formula used to calculate for peak factor used the value of 4.7 in the previous guideline and has been replaced with 3.4.

Image 2.1: Previous peak factor formula from Section 2 Planning, Material and Design: 2.1.14 Flow Rate Estimations, ii) peak Flow

Image 2.2: New peak factor formula from Chapter 2: Section 2.3, Page 2-29

Population equivalent

The population equivalent has been updated and more types of premises are added to the list. There are also some changes to the existing type of premises or establishments. 

Image 3.1: Previous population equivalent from Section 1 Introduction and General Planning Requirements: 1.5 Guidelines for Design Calculation

Image 3.2: New population equivalent from Chapter 3 (Part 1), Page 3-33 – 3-35

Image 3.3: New population equivalent from Chapter 3 (Part 2), Page 3-33 – 3-35

Land area requirements

The land area requirement for STP has also been updated in the new guideline. You may refer to the full table in the guideline accordingly.

Image 4.1: Previous land area requirement from Section 4 Requirement for Physical Design: 4.4 Land Area Requirements

Image 4.2: New land area requirement from Chapter 5, Page 5-51 – 5-53

Sewage characteristics

In the new guideline, SPAN introduced design influent value according to the PE range compared to previous guideline where the values are generalised.

Image 5.1: Previous design influent values from Section 3 Sewage Characteristic and Effluent Discharge Requirement : 3.3.2 Design Values.

Image 5.2: New design influent values from Chapter 2, Page 2-27

Image 5.3: Selection design step to determine influent value

Greenhouse gas (GHG) reduction targets

In this new guideline, SPAN introduced the usage of carbon footprint calculator to estimate the GHG emission. This is in line with the GHG reduction targets as part of efforts to support sustainability goals.