Discharge Factors are used to estimate the volume of sewage (trade waste and domestic sewage) discharged to the sewer network.
The Discharge Factor for a property is the ratio of sewage discharged to the sewerage system to the total water consumption (expressed as a decimal fraction).
This factor is used by Urban Utilities for the calculation of sewerage charges:
Discharge Factor = (Domestic Sewage + Trade Waste)/Total Water Consumption
The total water consumption includes water purchased from Urban Utilities, alternative water sources (e.g. roof water) and water that is introduced in process feedstocks (e.g. milk).
Some water is inevitably “lost” during domestic and trade waste processes, and these losses are accounted for by the discharge factor.
Losses may occur as a result of irrigation, evaporation of cooling tower feedwater, steam production, incorporation in products (e.g. soft drinks) or discharge to other waste management streams.
Discharge Factors are determined by Land Use Code and differ across property types and industries, as per the table below:
|LAND USE CODE
|1; 2; 3; 6; 7; 8; 10; 11; 12; 13; 14; 15; 16; 17; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 35a; 36; 37; 39; 42; 43; 45; 47; 48a; 51; 52a; 53; 54; 55; 57b; 60; 61; 70; 92; 94; 96; 97; 99
|Vacant Urban Land; Single Unit Dwelling; Multiple Dwelling, Outbuilding/Amenity; Guest House - Private; Community Title Scheme; Combined Multiple Dwelling and Shops; Shop (Single); Shops (>6 Shops); Shops 2-6 Shops; Shops - Main Retail; Shops - Secondary Retail; Drive In Shopping Centre; Restaurant; Residential Institution; Car Park; Retail Warehouse; Sales Area; Office(s); Funeral Parlour; Hospital/Convalescence Home; Warehouse and Bulk Store; Transport Terminal; Service Station; Fuel Depot; Wharf; Builders Yard; General Industry; Light Industry; Noxious/Offensive; Harbour Industry; Hotel/Tavern; Motel; Theatres/Cinemas; Theatres/Cinemas; Licensed Club; Sports Club/Facility - Default; Religious; Cemetery - Default; Relocatable Home Park; Art Gallery, Museum, Zoo; Library; Park and Garden - No Irrigation; Retirement Villages; Mixed Residential Purposes; Secondary Residential; Defence Force Establishment; Vacant Rural Land; Public Hospital; Welfare Home/Institution; Community Protection
|20; 41; 58
||Marina; Child Care; Educational
|18; 48e; 49; 50; 56; 63
||Special Tourist Attraction; Sports Club/Facility - Swimming Pool; Caravan Park; Other Club (Non-Business); Showground/Racecourse/Airfields; Boarding Kennels/Cattery
||Cold store/Ice works
|48c; 48d; 57a
||Sports Club/Facility - Pony Club; Sports Club/Facility - Bowls Club; Park and Garden - Default
|40; 44; 48b; 52b; 62; 64; 65; 86
||Extractive; Nursery; Sports Club/Facility - Irrigating Surfaces; Cemetery - Irrigated; Wholesale Production Nursery; Agriculture - Livestock Production; Agriculture - Crop Production; Horses
|19; 38; 91; 95
||Walkway; Advertising - Hoarding; Utility Installation; Reservoir/Dam/Bore
|For Trade Waste customers who discharge greater than 25kL BOD per day, Urban Utilities may use trade waste meters (or other discharge meters) to measure their Discharge Factor.
Review of discharge factors
Although standard Discharge Factors generally provide an appropriate estimate of the water use and disposal characteristics at a property, specific activities at the property can influence the true Discharge Factor and justify a review process.
Property owners or their agents can apply for a review of their Discharge Factor if they feel it isn’t representative of the amount of water discharged to sewer.
For example, relatively high rates of irrigation, feedwater to cooling towers or significant water retained in products can decrease the true discharge factor.
The use and disposal of water from alternative sources (e.g. roof water or bore water) or introduced in process feedstocks (e.g. milk) should also be accounted for and will increase the discharge factor.
Usually, an appropriate estimate of the Discharge Factor can be made and agreed between the owner and Urban Utilities.
As an alternative, the property owner or their agent may elect to install sewage discharge metering to provide a more accurate assessment of sewage volumes.
Before making the decision to apply for a review or install metering, property owners and agents should consider:
- The practicality of installing a sewage discharge meter or sub-meters needed to demonstrate the amount of sewer discharge.
- The costs involved compared to the likely benefits.
- The possibility that the standard Discharge Factor is accurate or favourable to the property owner or occupier.
Applications for review of Discharge Factors should be emailed to firstname.lastname@example.org
In assessing applications, Urban Utilities will refer to water consumption and trade waste records for the previous two years (where available).