EPANET++ is a free web application for modeling water distribution networks, an extension of EPANET.

Libraries

Holds the project's patterns, curves, pipe types, fittings lists, controls, and rules, one section each. Choose Water, Libraries to open it. An asset refers to a pattern, curve, pipe type, or fittings list by the ID of that item, and the item is created, edited, and deleted here. All are saved with the project, and Undo reverses an edit made here. The position and size of the box are kept in this browser only.

What each section holds

Patterns	A list of multipliers that repeats for as long as a run lasts, one multiplier for each pattern time step. A new pattern is 24 multipliers of 1. Pasting a spreadsheet column fills the Multipliers box. The default demand pattern is marked (default) and is chosen in Settings, Calculation, Hydraulics.
Curves	Four kinds, chosen as the Curve type: Pump head, Pump efficiency, Tank volume, and Valve head loss. The points are entered in a grid that accepts a pasted spreadsheet column or lines copied from an EPANET file. A pump head curve with one point or with three points that begin at zero flow is fitted, and the Equation line shows the fit; one point is read as the design point, with a shutoff head of 1.33334 times its head and a maximum flow of 2 times its flow, as EPANET reads it. Any other pump head curve, and each of the other kinds, joins its points with straight lines. A pump or valve states its curve in Properties, where the Curves link opens this section.
Pipe types	A definition of diameter, roughness, and reaction coefficients that several pipes refer to. A property may be left blank in the definition and then entered for each pipe. In Properties, the values a pipe type states are disabled, and Detach from pipe type copies them into the pipe and stops the pipe using the type.
Fittings	Lists of fittings with a quantity for each, added up to one minor (local) loss coefficient, k, for a pipe or pipe type. The fittings offered are the thirteen in Table 3.3 of the EPANET 2.2 user manual and Other fitting. Choosing one copies its coefficient into the row, where it can be changed.
Controls	One statement each, in EPANET syntax, as in LINK id OPEN IF NODE id BELOW value. Under each, the box states whether it was understood.
Rules	Several lines each, in EPANET syntax: RULE, IF, AND, OR, THEN, ELSE, and PRIORITY. Under each, the box states whether it was read.

Renaming, deleting, and what refers to an item

An ID is changed in its section. A blank ID, or an ID already used in the same section, is not accepted. Renaming an item moves every reference to it, in Base and in every scenario. For a pattern, the references are a junction's demand pattern and the pattern of each of its demand categories, a Customer's demand pattern, a reservoir's head pattern, a pump's speed pattern, and the default demand pattern.

A pattern that is in use can be deleted, and each reference to it is cleared. If it was the default demand pattern, a notice states what junctions with no pattern use now. A curve, pipe type, or fittings list that is in use is not deleted. The message names the assets that use it, and each must be given another curve, or detached from the type or list, first.

Libraries and scenarios

The Libraries are the same in every scenario. A scenario can point an asset at a different curve, pipe type, fittings list, or pattern, which is an override of that asset, but the contents of an item are not overridden. An edit to a pattern, curve, pipe type, fittings list, control, or rule changes it for every scenario, whichever scenario is open. The default demand pattern is a setting rather than an item, and a scenario can have its own.

A control or rule that names an asset which is inactive in the open scenario is ignored in that scenario's run, and the Libraries box lists it. One that names an asset the project does not have is also ignored, with a warning.

Controls and rules in a run

A control is one statement. A rule is several lines that begin with RULE. Keywords are typed in English whatever the language of the page, and numbers are in the units of the project. Add a control starts from a statement built from the network, which is then edited into the one intended.

Controls and rules change a result only in an extended-period simulation, that is, when Total run time is greater than 0. A steady-state solution is not changed by either. Rules are applied by the EPANET engine only. Both are saved with the project and written to an EPANET file.

Importing libraries from another project

File, Import…, Libraries… opens another project file and copies whole libraries from it into this project. An item whose name is already used here is skipped and listed, so nothing already here is changed. A warning is shown when the file and the project state a quantity in different units, and the items are imported as written. Pipe types that refer to a fittings list this project does not have are listed; import the fittings library from the same file to resolve them.

Example on Net1

Open the Net1 example and choose Water, Libraries. Patterns holds pattern 1, Demand Pattern, with 12 multipliers 2:00 apart, covering 24:00, marked (default). Curves holds curve 1, Pump Curve for Pump 9, a Pump head curve with one point, 1500 gpm at 250 ft. Controls holds two statements: the first opens Link 9 when Node 2 falls below 110, and the second closes it when Node 2 rises above 140. Rules holds two rules that test the clock time and the level of Tank 2.

Choose Water, Calculate, and then Water, Reports, Status changes. Pump L9 is now closed at 10:00, now open at 15:00, and now closed at 21:00, and Tank N2 is now emptying at 22:00. In Controls, change 140 to 135 in the second control and choose Water, Calculate again. The last closing moves to 20:00, and Tank N2 is now emptying at 21:00.

Points to note

• A pattern repeats for as long as a run lasts, so it need not cover the whole run.
• An EPANET file has no place for a pipe type or a fittings list. The file carries the numbers each pipe reads, and the export says which pipes were flattened.
• The position and size of the Libraries box are kept in this browser. The items are saved with the project.