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Population Equivalents (PE)

In order to design pipe network, pump stations and sewage treatment plants, estimates need to be made of the volumetric flow rate which will be expected to be carried, pumped and treated.

Such flow rates are measured in cubic metres per second and need to be calculated for both existing land use and for expected future development.

There are many methods for calculating expected flow rates. One method is to calculate a design parameter called the "population equivalent" (PE) of a catchment and convert this to a flow rate.

The PE is an estimate of the usage made of sewage facilities. It is not a measure of population.

For residential areas the population equivalent is calculated as five per dwelling and is a direct measurement of the population in an area.

However for commercial areas it is calculated from the floor area, which is considered to be proportional to the number of people using a premises during the day. In this case it does not reflect the population living in an area.

The following table shows how the PE is calculated.

Type of Establishment Population Equivalent
Residential 5 per house
Commercial :
  Includes offices, shopping complex,
  entertainment / recreational centres,
  restaurants, cafeteria and theatres
3 per 100m2 gross area
School / Educational Institutions :
- Day schools / Institutions
- Fully residential
- Partial residential

0.2 per student
1 per student
0.2 per non-residential student
1 per residential student
Hospitals 4 per bed
Hotel with dining and laundry facilities 4 per room
Factories, excluding process water 0.3 per staff
Market (Wet Type) 3 per stall
Market (Dry Type) 1 per stall
Petrol kiosks / Service stations 15 per toilet
Bus Terminal 4 per bus bay
Taxi Terminal 4 per taxi bay
Mosque / Church / Temple 0.2 per person
Stadium 0.2 per person
Swimming Pool or Sports Complex 0.5 per person
Public Toilet 15 per toilet
Airport 0.2 per passenger/day
0.3 per employee
Laundry 10 per machine
Prison 1 per person
Golf Course 20 per hole

The PE may be converted to a flow rate using a simple formula such as set out in Malaysian Standards 1228 (MS1228).