Room for
the Elephant

Case study · Water

A flushing program, built from the field

Procedure, field app, training and field sheet. Designed, built and tested by a working water operator.

See the toolsWorked example
SAME FLOW · 3,479 L/minTHREE MAIN SIZES SPEED IN THE MAIN 150 mm MAIN3.18m/sBIOFILM OFF200 mm MAIN1.79m/sBIOFILM OFF250 mm MAIN1.14m/sBIOFILM STAYS0.911.5SEDIMENTBIOFILM

Same hydrant, same flow. The bigger the main, the slower the water, and biofilm only lets go at about 1.5 m/s.

1 · Name it

Two things work against crews

Problem 1

The jet lies

An open hydrant always looks fast. The cleaning happens in the main, where the same water moves ten times slower. Most flushing is judged by the jet.

IN THE MAIN≈ 1.8 m/s AT THE JET≈ 18 m/s
Same flow, two speeds. This program measures the main.
Problem 2

Mixed mains, slow math

Many flushes run through more than one main size. Each section needs its own area, volume and velocity before the hydrant opens, and the largest main sets the flow.

150 mm · 120 mA = 0.785 × 0.150²V = A × 120 = 2,120 L200 mm · 200 mA = 0.785 × 0.200²V = A × 200 = 6,280 LLARGEST MAIN SETS THE FLOW150 mm · 80 mA = 0.785 × 0.150²V = A × 80 = 1,413 LQ = 1.5 m/s × A(200) = 2,920 L/minv = Q ÷ A → 2.67 · 1.50 · 2.67 m/st = 9,813 L ÷ 2,920 × 3 = 10.1 min11 stepsbefore the hydrant opens
The field app does all eleven steps as you type.

2 + 3 · Design and build it

Four pieces, one record

Everything follows the same five steps, Plan, Set up, Flush, Finish, Restore, and keeps the same record.

  1. 1
    ProcedureA six-page SOP with key numbers, the plan math step by step, and pitot and nozzle charts.
  2. 2
    Field appOffline phone app: live velocity in every pipe section, pass/fail limits, CSV, GeoJSON and JSON exports.
    Open it
  3. 3
    TrainingEight progressive lessons on the math, physics and hydraulics, with hand-calc practice in metric or imperial that helps operators understand their decisions.
    Open it
  4. 4
    Field sheetA one-page paper record that matches the app box for box. Simple, easy to capture and send to your database or the reverse.
    Open it

What it took

Field to data

  • HydraulicsFlow from pitot and nozzle readings, velocity in mixed main sizes, flush time by volume and exchanges.
  • Procedure writingA short SOP crews can follow, with the math shown so it can be checked.
  • Data designOne record per flush, a schema and data dictionary, ready for spreadsheets, GIS and work-order systems.
  • SoftwareAn offline web app built to the procedure, tested in the field.
  • TrainingSelf-paced lessons that teach operators to explain every number.

Worked example

One flush, start to finish

A three-section segment in a fictional district, planned, flushed and recorded.

Read the case study
PlanSet upFlushFinishRestore
Gauge30 psi
Flow3,479 L/min
Largest main200 mm
Velocity1.79 m/s
Exchanges2.4 of 3
Residual58 psi
All 3 sections ≥ 1.5 m/s

4 · Hand it over

Free to use

The tools are free for any operator. Remote setup for utilities, and a white-label licence for consultants, are on the implementation page.

See the toolsImplementation