Water Quality Simulation

Water Quality is a type of simulation that complements an extended-period hydraulic simulation by allowing you to dynamically track constituents or characteristics of the water flowing through the system. The simulation is run after the hydraulic simulation is complete, and it is based on the flow values that were obtained from it. The available water quality simulations are: Chemical (typically chlorine), Temperature, Water Age (how long, on average, since a water parcel entered the system), Source Trace (the percentage of water that originated in an arbitrary source point), Multi-Trace (multiple simultaneous source traces), and MSX (multiple species with advanced interactions).

To perform a water quality simulation:

1. Define the quality simulation type and global parameters in the Simulation Options.
2. Set the quality simulation timestep in the Simulation Time dialog. For best results, it is recommended that you set the Quality Timestep to 1/10th of the Hydraulic Timestep or smaller. However, if the Adaptive Mixing Resolution option is enabled, you can set the Quality Timestep to be as long as the Hydraulic Timestep.
3. Configure the sources. A quality source is a node in the network where the constituent is injected or modified. Node water quality sources can be defined in the Tools menu for nodes. If no explicit sources are defined, sources are assumed to have a concentration value of zero.

   • Chlorine: Sources are typically set in reservoirs, tanks, and junctions (with negative demand) that represent inputs from water treatment plants, as well as in any junctions that represent chlorine booster stations.

   • Temperature: Input nodes and any junctions that represent heating or chiller stations.
4. Configure initial values. Initial quality values are those at the beginning of the simulation. They can be defined in two ways:
   • Either, individually for each node in the Initial Water Quality dialog in the node's Tools menu.
   • Or, for the entire network by using a Water Quality State file (see Simulation Options).
5. Run a standard simulation as usual. See Run Manager for help.
6. Browse additional water quality output results as usual. See Analyzing Output Results for help.