A tank is a type of storage used in domestic, commercial and/or industrial settings to store water collected from surface runoff or sources such as greywater or blackwater waste streams. Once stored the water can be released in a controlled manner, and/or used to supply water demands.
Conceptually, the operation of a rainwater tank is identical to the operation of any tank-based storage infrastructure. The simulation scheme developed for Urban Developer is generic in its applicability to all forms of tank-based storage.
The tank allows for the inflow of rainwater as well as the provision of trickle top-up, triggered to start and stop at a user-specified tank level.
Inputs
• roof node (page 116) or other impervious area (page 110).There is no direct input capability for "topping-up" the tank; topup is controlled by a parameter in the tank property editor (see below). Inflow: Tank inflow is usually from a
The top-up function takes water from the mains supply, however in this version, the mains supply usage due to trickle top-up is not tracked in the mains supply aggregation. This functionality will be added in future versions of Urban Developer
Outputs
• Water Use (page 143) node per unit time. Supply out: The tank volume extracted from a
Link type (page 66): Demand
• Spill: The volume flowing out of the tank when the detention volume is exceeded.
Link type (page 66): Runoff
• Detention outflow: The flow from the overflow pipe at the invert of the detention volume, during a flood event.
Average Daily Model
In this model, the water use node uses monthly varying, average daily consumptions for indoor and outdoor use. It disaggregates the daily demand data to a sub-daily time-step using a non-dimensionalised diurnal pattern. A sample pattern is provided, however, you can specify your own. See the Water Use (page 143) node section and the diurnal pattern (page 162) file format specification for details on how to do this.
The disaggregated demand is then further portioned into different end-uses for both indoor and outdoor consumption. This enables supply sources to be selected for different end uses. You can also model demand management options by applying a demand reduction percentage to individual end-uses, to represent things such as water-efficient appliances, and
water saving practices. The discharge from consumption activities can also be apportioned to various water streams in the water use node.