24-hour and intermittent supply runs

Turn a snapshot into a 24 hour extended period run with a daily demand pattern, and model intermittent supply of a few hours a day.

A snapshot run (Total Duration 0) solves one instant. It is enough to check pressures at a chosen demand level, but tanks do not fill or drain, pumps do not switch, and demand does not change through the day. An extended period run solves the network hour by hour so you can see all of that.

An extended period run needs three things: a duration, a demand pattern, and time steps. Project > Set up a 24-Hour Run... asks for all three in plain words and writes them into the project in one go.

Step 1: Simulation type

Choice	Duration	Use it for
Single snapshot	0:00	One instant, for checking pressures at a chosen demand level.
24 hours	24:00	One day: the daily cycle of demand and tank levels.
48 hours	48:00	Two days: shows whether tanks end the day where they started.
7 days	168:00	A week: for water age and slow tank drift.

The window shows the project's current Total Duration at the top.

Step 2: Demand pattern

A pattern is a list of multipliers, one per hour, that makes each junction's base demand rise and fall. Choose one of three options:

Keep the project's patterns: leave patterns as they are.
Continuous supply, from the library: pick a ready-made 24 hour shape.
Intermittent supply windows: say when water is on, and PipePilot builds the pattern.

The library holds these patterns:

Pattern	ID	Shape
Urban 24x7 (morning and evening peaks)	URBAN24X7	Continuous supply in a town: a sharp 6 to 9 am peak, a smaller 6 to 8 pm peak and low night use. Peak multiplier 2.5.
Rural JJM continuous	RURALJJM	Continuous supply to household taps in a village (Jal Jeevan Mission): use bunched around early morning and evening chores. Peak multiplier 3.0.
Flat	FLAT	The same demand every hour. Useful to check a network before adding a daily shape.
Intermittent, 2 h morning + 2 h evening	INT2X2	Water on 6 to 8 am and 6 to 8 pm only. The whole day's volume is drawn in those 4 hours, so the multiplier inside them is 6.0.

The peak factors (2.5 urban, 3 rural) are from CPHEEO 2024 Table 2.7. The hour-by-hour shapes are illustrative, not measured. Where a town has its own bulk meter or SCADA record, build a pattern from that instead.

A chart previews the 24 multipliers, with the peak multiplier, the mean, and the hours of the day the water is on. Then give the pattern a Pattern ID and choose how it is used:

Make it the Default Pattern: every junction without a pattern of its own follows it.
Assign it to the N junctions with no pattern, where N is how many there are: writes the pattern onto each such junction directly.

Junctions that already have a pattern keep it either way. If the ID you type already exists, the window warns that the existing pattern will be replaced.

Intermittent supply

Many Indian towns supply water for a few hours a day. During those hours consumers fill sumps and overhead tanks, so the whole day's volume is drawn in a short time. PipePilot keeps the daily volume and squeezes it into the supply hours:

Press + Add window for each supply window, and give a Start hour (0 to 23) and a length in whole hours. Windows may wrap past midnight.
The multiplier inside the windows is 24 divided by the number of supply hours. Four hours of supply gives 24 / 4 = 6.0; outside the windows it is 0.
Daily volume factor scales the day when supply falls short of demand. 1 delivers the full daily demand; 0.8 delivers 80% of it.

The library pattern Intermittent, 2 h morning + 2 h evening is this rule applied to 6 to 8 am and 6 to 8 pm.

Multipliers of 6 or more put very high flows through the network, so pressures during supply hours fall sharply. In a real intermittent network, junctions with low pressure simply get less water. EPANET's default demand-driven analysis delivers the full demand anyway and reports negative pressures. To see how much water each junction really receives, set Demand Model to PDA on the Hydraulics page of Project > Analysis Options... and set Minimum Pressure and Required Pressure to suit the scheme.

Step 3: Time steps

Step	Default	Meaning
Hydraulic time step	1:00	How often EPANET re-solves flows and pressures. It also takes shorter steps by itself when a tank fills or empties or a control acts.
Pattern time step	1:00	How long each multiplier lasts. Fixed at 1:00 when you choose a library or intermittent pattern, because those have one value per hour.
Reporting time step	1:00	How often results are kept for the time slider, graphs and tables.
Quality time step	0:05	The step for water age and chlorine. It cannot be longer than the hydraulic step.

Times are entered as hours:minutes. Pattern Start and Report Start are left as they are; change them on the Times page of Project > Analysis Options....

Apply and run

Press Apply to write the setup into the project, or Apply and Run to write it and run straight away. Any problem (an empty pattern ID, a quality step longer than the hydraulic step) is shown at the bottom of the window before anything changes.

Then step through the day with the Time slider on the Browser's Map tab, or play it with the animation buttons. A Time Series graph of an ESR's level and of the pressure at a tail-end junction tells you most of what you need. See Running and reading results.

Base demand is the average, the pattern supplies the peak

EPANET multiplies each junction's base demand by its pattern. For an extended period run the base demand should be the average demand and the pattern should supply the peak. Do not also multiply the base demand by a peak factor, or the peak is counted twice. Demand allocation explains how to get the average demand from a population.