Purpose. Size tanks, sumps, wet wells, balance tanks, and storage reservoirs that receive flow continuously at varying rates. Typical applications: post-filtration re-lift tanks, inter-stage balance tanks, raw water break tanks.
What it does. Runs a 1-minute time-step simulation of inflow vs pump outflow over the chosen window. Inflow tracks per-filter contribution and applies backwash disturbances per the plant-flow control philosophy you select. Outflow is either VSD-controlled (level setpoints with a %/min ramp constraint) or fixed-speed cycling.
How to use. Set the inflow (constant value or 24-hour profile), filter count, and pump configuration. Pick a scenario — single backwash, repeated BW cycles, or N+1 (one filter offline for the whole sim). Watch the volume and flow charts — overflow and dry-run minutes are flagged in the alerts. Pumps are sized correctly when peak utilisation is under ~95% and there are no overflow / dry-run events.
Purpose. Size backwash settlement tanks for plants with a fill → settle → decant → desludge cycle. Calculates per-tank volume requirement, full cycle duration, lag between cycles, and minimum tank count needed so each tank empties before the next wash arrives at it.
What it does. Builds the cycle from a backwash batch fill, a settle hold, two decant rates separated by a switch level (% of fill volume), and a desludge phase. BW interval is derived from filter run time × filter count and rounded up to a practical 5-minute increment. Auto-sizing accepts up to 30 minutes of cycle overlap into the next interval (matches the Te Marua / Wainui sizing convention).
How to use. Set filter cycle, BW rate and duration, then tune settle / decant / desludge rates. Use the tank-count toggle for auto-size or manual override. Volume and Gantt charts show how multiple tanks stagger through their phases over a 24-hour window.
Purpose. Size a tank that receives discrete rapid fills and discharges slowly — without the settle / decant / desludge cycle of the Washwater tab. Typical applications: filter-to-waste (FTW) holding tanks where the first ~20 min of filter run is recycled to plant inlet, recycle tanks for slow side-stream return, and any holding tank capped on discharge rate.
What it does. Schedules multiple fill events across the simulation window (one per filter return, spaced by the filter cycle / N filters). Each event fills at the configured rate for the configured duration. Discharge runs continuously at either a fixed rate or as a percentage of plant inflow (so the return is bounded by the regulatory or process limit, typically ≤10% of plant flow).
How to use. Set fill event count, rate and duration. Choose discharge mode: Fixed rate for sized return pumps, or Proportional to plant inflow for ratio-controlled return where the constraint is a % of plant flow. In proportional mode the plant inflow can be a single constant or a custom 24-hour profile built from time segments (e.g. low overnight, two daytime peaks). The volume chart shows tank level over time; the flow chart shows fill, discharge, and (in proportional mode) the plant inflow reference. Adequate sizing means peak volume stays below capacity and the tank empties between events.
Purpose. Export results for documentation and resume work later.
Outputs.
Save and resume. Use the JSON export to snapshot a project, then drag the file back in via the import card to restore every input across all tabs.
Tick the tabs to include in the printed report. The browser print dialog will open with all selected tabs laid out for printing or saving as PDF.
Download per-minute simulation traces for the selected tabs as separate CSV files. Useful for further analysis in Excel.
Download all inputs across every tab as a single JSON file. Use the import card opposite to restore the project later.
Restore inputs from a previously saved project file. Overwrites all current values across every tab.
Snapshot of the headline outputs from each tab.
1-minute time-step mass balance on a post-filter sump. Inflow is built from the configured inflow (forward production) plus any drain-down water from filters currently in their post-BW drain phase. Outflow is either VSD-controlled (level-driven setpoints with a %/min ramp constraint) or fixed-speed cycling between start and stop level setpoints.
Inflow-during-BW models:
Other assumptions:
Each tank walks through FILL → SETTLE → DECANT1 → DECANT2 → DESLUDGE → IDLE phases. Wash events are scheduled at the BW interval and assigned to the first IDLE tank. The simulator tracks tank volume, missed-wash events, and overflow.
Key assumptions:
Generic batch tank with rapid fill events and continuous discharge. Each event adds at the fill rate for the fill duration. Discharge runs either at a fixed rate or as a percentage of the (constant or diurnal) plant inflow.
Key assumptions: