Equivalent Tenements Explained

An Equivalent Tenement (ET) is a measure of the load a property places on the sewerage system. One ET is considered to be the sewage discharge from an average single residential house, under dry weather flows. This has been determined to be 200kL/ET/annum. ET rates for different land uses are calculated as being a factor of this average sewage discharge rate.

In relation to non-residential properties, different ET rates are applied to various property attributes, including building area, land size, number of occupants, general public entertainment facilities, hospital beds and amenities. These ET rates and attributes are then used to undertake an assessment of the number of ETs for that property.

Where a property has multiple activities on the land parcel the ET rates and assessment are based on each specific type of activity.
This list of categories is not exhaustive and consequently TasWater has included the ability to assess on an ad hoc, case by case basis if the circumstances warrant.
It should be noted that discharge of non-domestic liquid trade waste is recouped separately through the application and payment of trade waste charges.

Our approach is underpinned by the Section 64 Determinations of Equivalent Tenements guidelines produced by the NSW Water Directorate and available here. The NSW Water Directorate guidelines indicate it is preferable to apply localised ET figures as there are variances in differing jurisdictions. TasWater has adopted statewide ET rates, consistent with the application of postage stamp pricing across the state, and made adjustments to some rates to best reflect Tasmanian circumstances. Our justification of ET rates for property types that differ from those contained in the NSW Water Directorate's 2017 Section 64 Determinations of Equivalent Tenements Guidelines are available.

Equivalent Tenement assessment process

With respect to assessing a customer’s property calculated ETs, the following steps are undertaken: 

1. A combination of data sources such as site visits, local knowledge, google maps, direct customer contact and council data, are used to ascertain the property type and associated property attributes. ETs for identified non-residential customers, e.g. commercial, industrial, primary industry, and community services, to be determined based on their respective category and, within that category, the other relevant parameters including number of beds or rooms, number of staff and students, and gross floor area and/or applicable amenities.

2. Attribute a default one (1) ET to all identified standard residential customers.

3. Identify customers who have a property within Serviced Land that is not physically connected to TasWater’s infrastructure but which has the ability to connect. While the property will have a minimum of one ET, these customers will be charged at 60 per cent of the standard ET rate for a residential dwelling.

A schedule of the ET rates for different industries/property use types is provided in Appendix 13 of our PSP3 document.

Equivalent Tenement rates and sewerage charges 

ET assessments are used to calculate a customer’s fixed sewerage target charge. The fixed sewerage charge covers costs associated with treatment and disposal of domestic sewage.

A customer’s fixed sewerage target charges increase proportionally with the ET assessment, with non-residential properties charged based on the load they could potentially place on the sewerage system relative to a single residential dwelling.
For sewerage charging purposes, no customer can be less than 1 ET, however if a property is within Serviced Land but not connected that customer will receive an unconnected sewerage service charge, which equates to 60 per cent of the full fixed sewerage target charge.

The practical application of the ET methodology means that if a property is deemed to be capable of discharging twice as much sewage into the sewerage system, it will be assessed as 2 ETs and the target price will be twice the standard fixed sewerage charge. Similarly, if the customer could discharge 50 times as much as a residential dwelling it will be assessed as 50 ETs and the target price will be 50 times the standard fixed sewerage charge.

For the purpose of calculating sewerage charges, the Economic Regulator has approved that a customer’s ET assessment will result in a minimum of one ET being applied, although ET rates for different property types may be less than one.

Equivalent Tenement assessment

TasWater has arrangements in place for customers to have their ET calculation reassessed if they believe it is inaccurate.

An ET reassessment may result in an increase or decrease in the ET rates and therefore the applicable target price. The new rates and target price will be applied to the customer’s account from the next billing period, with the charges transitioning (consistent with the approved price constraints) at the start of the next financial year.

If you believe that the data used to calculate the ET total is inaccurate.  Please contact us by email on enquiries@taswater.com.au with 'ET' as the subject heading or phone 13 6992.