Track water age, trace supply blending, and simulate chlorine decay and multi-species reactions through your network using the standard EPANET engine.
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Water age (h)
Water quality
Age
Extended period · 72 h
Taste and odor complaints, depleted chlorine residuals, and discolored water surface at the customer tap, but their root causes lie upstream in oversized mains, dead ends, and poorly mixed storage tanks. Because a calibrated hydraulic model already dictates flow paths and travel times, water quality analysis simply puts those mechanics to work.
epanet-js executes the complete suite of standard EPANET quality analyses: tracking water age to identify stagnation, performing source traces to map supply boundaries, and running chemical routing to monitor constituent concentrations (like chlorine) as they propagate and decay across the distribution system.
In multi-source distribution systems, the boundary between different treatment plant supplies fluctuates constantly as diurnal demands rise and fall. A source trace computes the exact percentage of water originating from a designated supply node for every junction at every timestep.
This provides direct operational intelligence: verifying which pressure zones receive specific blended ratios, predicting the propagation of a new supply switchover, and isolating the footprint of a water quality complaint. If a localized taste issue maps perfectly to a single source's trace footprint, you know exactly where to investigate.
Source
Disinfectant residuals decay dynamically through bulk water reactions and pipe wall interactions. By modeling chlorine as a reactive constituent, you can visualize residual concentrations at every node over time—identifying network extremities and low-demand loops that drop below regulatory minimums before physical sampling flags a violation.
Simulate corrective actions before implementation. Adjust the dosing concentration at the treatment works or site a new booster chlorination station mid-network, then re-run the simulation to verify that target residuals are restored without over-dosing upstream customers.
Chlorine residual
mg/l
Residual vs distance from works
≥ 0.2 mg/l network-wide
Effective flushing requires sufficient velocity to scour biofilm and sediment from the pipe wall. Whether a flush succeeds depends entirely on which valves are isolated and which hydrants are opened. Use the model to design a unidirectional flushing sequence and verify that every pipe segment achieves the target scour velocity.
By simulating the exact hydrant and valve operations, you can identify mains that fail to reach scouring velocity, adjust the isolation sequence directly in the software, and generate a validated UDF plan. Field teams get an optimized sequence that minimizes non-revenue water (NRW) while ensuring clean pipes.
Flushing sequence
UDF
Advanced water quality challenges—such as chloramine decay, nitrification, or disinfection byproduct (DBP) formation—involve complex interacting chemistry that cannot be modeled as a simple first-order decay.
epanet-js natively integrates the EPANET Multi-Species Extension (MSX). This allows you to define multiple interacting constituents, specify reaction rate expressions, and simulate complex chemical dynamics reacting with each other and the pipe wall concurrently with network hydraulics.
epanet-js runs the official EPANET 2.3.5 toolkit unmodified, ensuring your water quality results match industry-standard calculations exactly.
Simulate water age, source blending, and chemical transport and decay—including full Multi-Species Extension (MSX) support—in one workspace.
Watch water quality propagate across the network map at every timestep, making stagnation zones and low residual boundaries immediately obvious.
Export constituent concentrations, age, and trace percentages as full time-series data to CSV or XLSX for reporting and compliance tracking.
Run a water age or source trace analysis on your own model in minutes. Launch epanet-js free, or book a demo with our engineering team.
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Water quality in epanet-js utilizes the exact same network file as your hydraulic simulations. There is no secondary software to license, and no need to maintain disconnected model copies. Build your network, calibrate the hydraulics, and execute quality runs directly from the same workspace.
It fits naturally alongside your broader workflow: operational modeling provides the temporal controls and extended period simulations that quality routing depends on, while calibration ensures your velocities and travel times are physically accurate before you superimpose chemistry onto them.
See how water quality connects to the rest of the modeling lifecycle.
Frequently asked questions about water quality modeling.
Simulate water age, map source traces, and track chlorine residuals directly on your network. Launch epanet-js or schedule a technical walk-through.
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