How to read an e-plan

Find information about how to interpret an e-plan, and determine the location of our sewer mains and the connection points located on them.

It is important to accurately interpret e-plans to make sure that your building and plumbing work does not damage our pipelines.

While e-plans help to locate to pipelines, to prevent damage during works you must physically confirm the location of all pipelines before commencing mechanical excavation or boring.

To determine the size and material of a nearby sewer main, please refer to the text running parallel to the main located on our maps as shown below. This text identifies the size of the main in millimetres and its main material. For example: 150P equals 150mm and un-plasticised Polyvinyl Chloride.

Sewer main diagram

Sewer mains are constructed from many different materials for different circumstances. Common materials used today are PVC and MDPE, however there are many other materials in use.

 Common sewer main material abbreviations
AC – Asbestos Cement PVC – Polyvinyl Chloride 
CI – Cast Iron RA – Resin Aggregate
DI – Ductile Iron RC – Reinforced Concrete
MDPE – Medium Density Polyethylene S – Mild Steel Cement Lined
P – Un-plasticised Polyvinyl Chloride VC – Vitreous Clay 

To determine the depth of a nearby sewer main, you will need to locate the nearest access chamber and its details.

To calculate the depth of the sewer you must deduct the sewer main invert level from the access chamber lid level.

Sewer main diagram 

Access Chamber Lid level - Sewer Main Invert = Sewer Main Depth (11.99 - 10.14 = 1.85)

In this example, the sewer main located at the rear of the property with the access chamber located on it is approximately 1.85m deep.

To calculate a sewer main alignment you need to locate the nearest access chamber (manhole) to the property represented on our plans by the symbols below.  Each access or maintenance chamber will have a square or circle nearby providing the chamber details

Calculate sewer main alignment

A - Along - The distance along a boundary from an intersection of boundaries (E.g. 7.0m along from boundary SE direction)

F - From - The distance  at right angles from a boundary (e.g. 2.0m from SW direction)

When there is an * located next to any of the distances or lid levels it means the distance or lid level is an estimate only and has not been confirmed. In this scenario it is necessary to have a site survey completed to determine the exact location of the main before any planning or construction begins.

For information about building near sewers and determining the setbacks involved, please refer to our Residential guidelines for designers document and visit our section on Working near our assets.

Locating a sewer connection point?

In older suburbs, the sewer connection point may not have been brought into the property, or up to 1 metre (m) below ground level. When doing plumbing work, you need to correctly interpret the e-plan, taking this into consideration.

Sewer e-plan diagram

In the above diagram, the connection for Lot 517 is shown outside the property line and the dimensions show that the connection point is 37.4m from the downstream manhole and has been brought in 2.7m and up 1.9m from the sewer line.

For Lot 111, the diagram indicates the connection point is 2.7m from the downstream manhole and has been brought in 1.3m and up 1.9m from the sewer line.