Topic
Water
81 guides across the knowledge base.
Sequencers
Step-based control for operations that always run in the same order: backwash, pump and valve startup, batch makeup, membrane cleans. What every step needs, three ways to implement one, handling faults and power loss mid-sequence, and what the HMI shows.
10 min readUpdated Sep 5, 2026
Control Strategies
Choosing how a loop is controlled before choosing how to program it: on-off with deadband, staging, PID, ratio and feedforward, cascade, split range, and override, with the water and wastewater applications each fits and the questions that pick between them.
11 min readUpdated Sep 5, 2026
Sequential Function Chart
The IEC 61131-3 language for sequences: steps, transitions, actions and their qualifiers, alternative and simultaneous branches, where it fits in water and wastewater, and the rules that keep a chart from sticking in a step.
9 min readUpdated Sep 5, 2026
Modicon M340
Field notes on the Schneider Electric Modicon M340, a rack-based mid-range controller common in water plants: rack and CPU layout, X80 I/O, memory card behavior, Ethernet and serial communications, programming in Control Expert, and what to check on site.
8 min readUpdated Sep 5, 2026
Modicon M580
Field notes on the Schneider Electric Modicon M580, the Ethernet-backplane controller at the top of the range: remote I/O drops on a ring, hot standby CPUs, built-in security features, the networks it defines, Quantum migration, and what to check on site.
9 min readUpdated Sep 5, 2026
ControlLogix
Field notes on the Rockwell Automation ControlLogix, the chassis-based controller of larger water plants: chassis and modules, tag-based memory and tasks, EtherNet/IP and older networks, controller redundancy, version matching, and what to check on site.
9 min readUpdated Sep 5, 2026
Engineering Units
Choosing and documenting the units a tag carries: where the unit is decided, how it flows from transmitter range to controller scaling to screen and historian, the conventions used in water and wastewater, and the mismatches that put a wrong number on screen.
7 min readUpdated Sep 5, 2026
DNP3
The protocol built for utility telemetry: master and outstation, static and event data classes, unsolicited reporting, time-stamped events, and why it suits slow links that Modbus does not.
8 min readUpdated Sep 5, 2026
Reporting from the Historian
Turning history into the reports a utility must produce: the monthly operating report, compliance reports for the regulator, daily operator summaries, pump run and energy reports, the calculations behind daily minimums, maximums, and totals, handling bad quality and gaps, and building reports once so they run every month without an engineer.
9 min readUpdated Sep 5, 2026
Long-Term Storage
Keeping historian data for years: a retention policy by data class that follows the record rules, tiered storage from online to offline copies, downsampling, archive management, exports that outlive the historian, and the annual proof that old data reads.
9 min readUpdated Sep 5, 2026
VTScada
Field notes on VTScada, the Trihedral platform widely used by municipal water utilities: the all-in-one design with historian, alarm notification, and thin clients built in, server redundancy, application versioning, telemetry drivers, and licensing by tags.
8 min readUpdated Sep 5, 2026
GE iFIX
Field notes on iFIX, the long-established SCADA from the Intellution and GE lineage now sold by GE Vernova: SCADA nodes and the process database, I/O drivers, view and web clients, the Proficy Historian, enhanced failover, scripting, and licensing by points.
8 min readUpdated Sep 5, 2026
AVEVA
Field notes on the AVEVA operations software family, formerly Wonderware: InTouch HMI, System Platform and its object model, the Historian, Plant SCADA from the Citect lineage, and AVEVA Edge. Which product does what, and what to check on site.
8 min readUpdated Sep 5, 2026
Schneider SCADA
Field notes on Schneider Electric SCADA for water: EcoStruxure Geo SCADA Expert, formerly ClearSCADA, the telemetry platform built around DNP3 events, an object database, and hot standby servers, with SCADAPack RTUs, and how it relates to the AVEVA products.
8 min readUpdated Sep 5, 2026
Hydrostatic Level Measurement
Measuring level from the pressure of the liquid above a sensor: submersible transducers, bubblers, and base-mounted transmitters, the density assumption behind all of them, venting, installation, and what makes them drift.
8 min readUpdated Sep 5, 2026
Ultrasonic Level Measurement
Non-contact level by time of flight: how the sensor works, the blanking zone and beam angle, temperature compensation, the surfaces and vapors that defeat it, mounting rules, and what to do when it loses its echo.
8 min readUpdated Sep 5, 2026
Pressure Transmitters
Gauge, absolute, and differential pressure transmitters: how they sense, how range, turndown, and accuracy specifications work, the process connection and its accessories, and the installation errors that show up as calibration problems.
8 min readUpdated Sep 5, 2026
Chlorine Residual Analyzers
Amperometric and colorimetric residual analyzers: what each measures, free versus total chlorine, pH and flow dependence, sample line design, calibration against a DPD grab sample, and using the signal for feed control.
11 min readUpdated Sep 5, 2026
pH Measurement
Glass electrodes, reference junctions, and why pH is the measurement that drifts: how the sensor works, temperature compensation, two-point buffer calibration, mounting rules, the failure modes of the reference, and using the signal for chemical feed control.
11 min readUpdated Sep 5, 2026
Turbidity Measurement
Nephelometric turbidimeters for filter effluent and raw water: how 90-degree scattering is measured, the methods and the NTU, low-range versus high-range instruments, bubbles and the debubbler, formazin calibration and verification standards, and the compliance record the instrument exists to produce.
11 min readUpdated Sep 5, 2026
Impulse Lines
The tubing between the process tap and the pressure or DP transmitter, and everything that goes wrong in it: slope and routing for liquid and gas, elevation head and how to correct for it, air and condensate, blocking and manifold valves, freezing, plugging on dirty service, and the diaphragm seal alternative.
9 min readUpdated Sep 5, 2026
Ultrasonic Flowmeters
Transit-time and Doppler ultrasonic flow measurement: how each works, which liquids each suits, clamp-on versus wetted transducers, the pipe data the meter needs, the accuracy to expect, and the installation details that decide whether to trust the reading.
10 min readUpdated Sep 5, 2026
Flowmeter Installation
The installation rules that decide whether a flowmeter reads correctly: straight run by meter type, keeping the pipe full, orientation, velocity range, grounding for magnetic meters, isolation and access, and the commissioning checks that prove the meter.
10 min readUpdated Sep 5, 2026
Flow Troubleshooting
A method for a flow reading that is wrong, noisy, zero, or disputed: establish the truth with an independent check, separate installation from configuration from signal chain, then the specific checks for magnetic, ultrasonic, and DP meters.
10 min readUpdated Sep 5, 2026
Differential Pressure Level
Measuring level in a closed or pressurized vessel with a DP transmitter: high and low side connections, dry legs and wet legs, zero suppression and elevation, the range calculation with a worked example, remote seals, and the density dependence.
10 min readUpdated Sep 5, 2026
Level Troubleshooting
A method for a level reading that is wrong, frozen, jumping, or lost: establish the true level, check the signal chain and configuration, then the checks for ultrasonic, radar, hydrostatic, DP, and float instruments, and the failure behavior to design in.
10 min readUpdated Sep 5, 2026
Differential Pressure
The differential pressure transmitter as an instrument: what it measures, static and overrange ratings, the three-valve manifold and the order of operations that protects the cell, and the applications from filter head loss to membrane TMP, flow, and level.
9 min readUpdated Sep 5, 2026
Pressure Transmitter Installation
Where and how to install a pressure transmitter so it reads the process and not its own plumbing: tap location, mounting above or below the tap, isolation and bleed valves, line slope, pulsation, elevation, freeze protection, seals, vibration, and sun.
10 min readUpdated Sep 5, 2026
Pressure Calibration
What calibrating a pressure transmitter means: as-found and as-left, the five-point test and hysteresis, tolerance and the reference standard, sensor trim versus output trim versus reranging on a smart transmitter, gauge versus absolute, and intervals.
10 min readUpdated Sep 5, 2026
Ammonia Analyzers
Online ammonia measurement in water and wastewater: ion-selective probes, gas-sensing electrodes, and wet-chemistry analyzers, what each is good for, the interferences that decide accuracy, and the maintenance and calibration it demands.
9 min readUpdated Sep 5, 2026
Conductivity
Conductivity measurement in water systems: what it indicates, contacting and inductive sensors, cell constants and ranges, temperature compensation, the relation to total dissolved solids, uses from membrane monitoring to blending, and fouling problems.
8 min readUpdated Sep 5, 2026
Nitrate Analyzers
Online nitrate measurement: ultraviolet absorbance probes and analyzers, ion-selective electrodes, and wet chemistry, the interferences from organics, turbidity, and chloride, the uses in denitrification and source monitoring, and maintenance.
8 min readUpdated Sep 5, 2026
ORP
Oxidation-reduction potential: what the millivolt reading means and does not, the platinum and reference pair, uses in dechlorination control, disinfection indication, anoxic monitoring, and chemical treatment, checking with standards, and electrode drift.
7 min readUpdated Sep 5, 2026
Distribution Pressure Control
How a booster or high service pump station holds discharge pressure with variable speed pumps, how pumps are staged, and what stops the system hunting.
9 min readUpdated Sep 5, 2026
Tank Level Control
How a storage tank is filled and drawn on level setpoints, how the setpoints are chosen to keep the water turning over, and what the station does when the tank stops talking.
8 min readUpdated Sep 5, 2026
Well Pump Control
Controlling a groundwater well: submersible and line-shaft turbine pumps, the pump-to-waste start, drawdown and the low-water cutoff, cycling limits from the well and the aquifer, and what the controller monitors to protect a pump that cannot be seen.
10 min readUpdated Sep 5, 2026
Booster Pump Stations
Inline stations that raise pressure from one zone to another: suction pressure protection, discharge pressure control with drives, staging, the hydropneumatic tank alternative, surge and check valve behavior, and the interlocks that keep a booster from collapsing the zone it draws from.
9 min readUpdated Sep 5, 2026
Elevated Tank Control
The tank on legs that sets the zone pressure: how level equals pressure, the operating band, the altitude valve and its telemetry, turnover for water quality, filling by pumps far away, freeze protection, and what the level signal does when the tank is holding the system together.
10 min readUpdated Sep 5, 2026
Disinfection Control
Controlling chlorine and chloramine dosing at a water plant: the CT concept and how contact time is credited, flow-paced and residual-trimmed feed, gas, hypochlorite, and on-site generation systems, the point-of-entry residual as the compliance measurement, and the interlocks that stop a feed system from over- or under-dosing.
11 min readUpdated Sep 5, 2026
Raw Water
Controlling the front of a surface water plant: intake and screens, low-lift pumping, the raw water flow that paces the whole plant, the online quality instruments that warn of a changing source, and the alarms and ramp limits that keep the train stable.
9 min readUpdated Sep 5, 2026
Wells
Operating a wellfield as a water source: selecting and rotating wells, pump-to-waste on start, drawdown and specific capacity, wellhead chemical feed, blending for nitrate or arsenic, the telemetry a well needs, and the interlocks that protect the pump.
10 min readUpdated Sep 5, 2026
Aeration
Aeration in drinking water treatment: stripping carbon dioxide, hydrogen sulfide, radon, and volatile organics, and oxidizing iron and manganese ahead of filtration. The aerator types, what each needs from the control system, the pH shift, and the interlocks.
9 min readUpdated Sep 5, 2026
Filtration
Controlling gravity and pressure filters: effluent rate and level control, head loss and turbidity on every filter, the backwash triggers and sequence, filter-to-waste and ripening, the turbidity rules that filter monitoring answers to, and the operator view.
11 min readUpdated Sep 5, 2026
Chemical Feed
Chemical feed from the control side: the chemicals and where they go, metering pumps and dry feeders, flow pacing with residual trim, the dose arithmetic, day tanks and drawdown tests, loss-of-feed detection, interlocks, and overfeed protection.
11 min readUpdated Sep 5, 2026
Finished Water Storage
Storage inside the plant: the clearwell that provides contact time and high service suction, backwash supply tanks, and how their levels drive production and pumping. The contact time calculation and the minimum level it demands, water age, and alarms.
9 min readUpdated Sep 5, 2026
High Service Pumping
Pumping finished water into distribution: the control modes of tank level, pressure, and flow, how they interact with the clearwell and contact time, staging and surge, the telemetry the station depends on and its fallback, energy scheduling, and the alarms.
10 min readUpdated Sep 5, 2026
High Service Pumps
The pumps that carry finished water into distribution: types, the pump curve against the system curve, best efficiency point, the affinity laws and where a drive pays, parallel operation, valves, protection, and the efficiency monitoring that shows wear.
11 min readUpdated Sep 5, 2026
VFD Control for Water Pumping
Variable speed pumping and where it earns its cost: the affinity laws and how static head limits the savings, the minimum speed a pump can run, pressure, flow, and level control with a drive, and how to estimate the savings before buying.
9 min readUpdated Sep 5, 2026
Flow Control in Water Pumping
Controlling the flow a pumping system delivers: speed against valves, flow-paced pumping to a treatment rate, the flow loop with its ramp limits and its meter placement, and the loop tuning that keeps a flow controller steady.
8 min readUpdated Sep 5, 2026
Ground Storage Tanks
Controls for ground storage tanks: level measurement and its datum, filling from wells and treatment by pump control or altitude valve, and the telemetry that ties the tank to the system.
8 min readUpdated Sep 5, 2026
Pump Sequencing for Storage
Sequencing the pumps that fill and draw from storage: staging on level bands, rotating wells and sources for even use and water quality, time-of-day and demand-based scheduling, and the records that show the sequence is doing its job.
8 min readUpdated Sep 5, 2026
Reverse Osmosis
Reverse osmosis from the controls side: what the skid contains, the instruments that matter, the numbers an operator watches, recovery, rejection, normalized permeate flow, and the trends that say when the membranes need cleaning or replacement.
10 min readUpdated Sep 5, 2026
Nanofiltration
Nanofiltration from the controls side: how it differs from reverse osmosis in pressure, recovery, and what it removes, the softening and color removal applications where it dominates, and trends that are shared with reverse osmosis and the ones that differ.
8 min readUpdated Sep 5, 2026
Membrane Control
The control system of a membrane skid: the loops for permeate flow, recovery, and dosing, the permissives and trips, the start, run, flush, and shutdown sequences, and the data the operators and the membrane supplier need from the historian.
9 min readUpdated Sep 5, 2026
Clean-in-Place
Cleaning membranes in place: the triggers from the normalized trends, the low pH clean for scale and the high pH clean for organics and biofouling, the sequence of flush, heat, recirculate, soak, and rinse, and how automation makes cleaning repeatable.
9 min readUpdated Sep 5, 2026
Membrane Feed Pumps
The high-pressure feed pumps of a membrane plant: multistage centrifugal pumps on drives, the pressure ramp that protects the elements, suction protection and the cartridge filters ahead of them, and the maintenance that the trends point to.
8 min readUpdated Sep 5, 2026
Concentrate Systems
Handling the concentrate a membrane plant produces: the concentrate valve and the recovery it sets, flow and quality monitoring for the permit, the disposal routes, surface discharge, sewer, and the alarms and records a concentrate permit expects.
8 min readUpdated Sep 5, 2026
Small Utility Cybersecurity Priorities
What a utility with a few operators and no IT department should do first: the ten measures that remove most of the risk for the least money and time, in the order to do them, with what each one costs, what it prevents, and how to know it is done.
10 min readUpdated Sep 5, 2026
OT Risk Assessment
Ranking what could go wrong in a control system and what it would cost: the consequence-first method for utilities, the assets and scenarios to list, likelihood without pretending to know it, the risk matrix, and turning the ranked list into a work plan.
10 min readUpdated Sep 5, 2026
OT Incident Response Plan
The plan for the day the control system is not trusted: who decides, the triggers, the first hour, isolating without stopping treatment, running by hand, preserving evidence, who to notify and when, recovery from backups, and the exercise that makes it real.
10 min readUpdated Sep 5, 2026
Security Program Basics
What a control system security program is for a utility that has never had one: a named owner, an inventory, a risk assessment, a few policies, baseline controls, training, vendor rules, an exercised incident plan, and a first-year plan for a small staff.
10 min readUpdated Sep 5, 2026
Manual Operation Procedures
Written procedures for running the plant and the remote sites without the SCADA or the controllers: what to read and set by hand, how often to check, what to log, chemical dosing from a flow reading, when to stop, staffing, and the drill that proves them.
9 min readUpdated Sep 5, 2026
Reporting Requirements
Who a water or wastewater utility must tell about a cyber incident, how fast, and what to say: the federal critical infrastructure reporting rule, state laws, the drinking water regulator, public notification, law enforcement, the sector center, and insurers.
9 min readUpdated Sep 5, 2026
AWIA Requirements
What the 2018 water infrastructure act requires of community water systems: a risk and resilience assessment and an emergency response plan, certified on a schedule by size and repeated every five years, with cybersecurity named in both, and who is covered.
9 min readUpdated Sep 5, 2026
EPA Guidance
What the federal environmental agency provides to water and wastewater utilities on cybersecurity and what it expects: the free assessment, the checklist aligned with federal goals, joint incident response guidance, the enforcement position, and how to use it.
8 min readUpdated Sep 5, 2026
CISA Resources
What the federal cybersecurity agency provides to utilities without charge: the performance goals, regional advisors, external vulnerability scanning, control system advisories, the exploited catalog, a self-assessment tool, exercises, and incident reporting.
8 min readUpdated Sep 5, 2026
Valve Will Not Reach Position
A valve commanded to a position that stops short: an obstruction or a seat the actuator cannot push through, travel limits or a positioner span set wrong, a stem binding, an actuator undersized or out of air, or a command signal that does not span.
8 min readUpdated Sep 5, 2026
Valve Slow to Respond
A valve that takes far longer to move than it should: a pneumatic supply restricted or leaking; a positioner tuned slow; an electric actuator whose speed is fixed; a stem binding in cold or packing; or a rate-limited output. Measuring the stroke time.
8 min readUpdated Sep 5, 2026
Position Feedback Wrong
The HMI says one position and the valve is at another: a feedback potentiometer worn or miscalibrated, a linkage that slipped, scaling that does not match, a reversed signal, limits set wrong, or noise. Comparing indicator, feedback, and process.
8 min readUpdated Sep 5, 2026
Actuator Torque Fault
An electric actuator that trips on torque: at the seat because the seating mode or setting is wrong, in mid-travel because something is in the way or the stem binds, or under flow because the differential exceeds the sizing. The checks before a reset.
8 min readUpdated Sep 5, 2026
CISA Guidance as a Reference
How the federal cybersecurity agency publications serve as reference standards for a utility: the performance goals as a baseline for policy and procurement, the water sector goals, secure-by-design principles for vendors, and the advisories.
8 min readUpdated Sep 5, 2026
EPA Rules and Their Control System Implications
The federal environmental agency rules that shape what a water or wastewater control system must measure, record, and report: the surface water rules, residual and byproduct rules, groundwater and lead rules, discharge permits, and record retention.
10 min readUpdated Sep 5, 2026
AWWA Standards and Manuals
What the American Water Works Association publishes that a control engineer uses: the instrumentation and control manual, the risk and resilience standard behind the act assessments, the security and emergency standards, and the cybersecurity tool.
8 min readUpdated Sep 5, 2026
What a Small Utility Should Ask Before Buying SCADA
A utility with a plant, a few dozen remote sites, and two operators on call is buying a system it will live with for twenty years. The questions that decide whether it works out, and they are not about features: licensing, staffing, and the exit.
9 min readUpdated Sep 5, 2026
The Tank Level Trend Tells the Whole Story
One trend, a storage tank level over a week, holds most of what an operator needs to know about a water system: demand, source capacity, leaks, pump health, water age, and why it deserves a permanent place on the main screen.
8 min readUpdated Sep 5, 2026
Calibration Is a Program, Not an Event
An instrument calibrated once at startup and again when someone complains is an instrument whose readings cannot be trusted in between. What a calibration program is, and how a small utility runs one without a full-time instrument technician.
8 min readUpdated Sep 5, 2026
The Knowledge That Leaves With the Retiring Technician
Water and wastewater utilities are losing the people who know how their control systems actually work, and a practical program for capturing it while there is still someone to ask.
8 min readUpdated Sep 5, 2026
What Integrator Consolidation Means for a Small Utility
The regional controls integrator that built a utility system over twenty years is being bought, merged, or closed, and how to stop depending on any single firm for the system it owns.
7 min readUpdated Sep 5, 2026
The Chlorine Residual Loop Is Slower Than You Think
Residual control loops oscillate because the measurement arrives minutes after the dose changes, and the tuning was done as if it arrived at once. Where the delay comes from, and how to control a loop whose dead time is longer than its response.
10 min readUpdated Sep 5, 2026
Water and Wastewater Utility Threat Landscape
What has actually happened at water utilities, what those incidents had in common, and the small number of controls that would have prevented most of them.
8 min readUpdated Aug 28, 2026
Magnetic Flowmeters
Faraday's law applied to a pipe: how a mag meter works, the conductivity and full-pipe requirements, and why grounding decides whether it reads.
8 min readUpdated Aug 1, 2026
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