Reservoir Capacity Calculator
Estimate operational storage from daily demand and storage duration, then show explicit contingency and unusable-volume allowances.
Use the Reservoir Capacity Calculator
Estimate operational storage from daily demand and storage duration, then show explicit contingency and unusable-volume allowances.
Calculations happen locally in your browser. ToolLott does not send these inputs to a server for this tool.
Preliminary planning or arithmetic calculation only. Confirm project inputs, units, operating assumptions and applicable requirements before procurement, construction or operational decisions.
How to use it
Replace the worked-example values with actual project data. Review the intermediate quantities and visible assumptions before using the result elsewhere.
How the Reservoir Capacity Calculator works
Estimate operational storage from daily demand and storage duration, then show explicit contingency and unusable-volume allowances. The methodology below exposes the production equation, a QA-verified worked example and the boundary between this screen and detailed design.
Calculation breakdown
ToolLott will explain the current inputs and displayed result here.
Operational reservoir storage
The production engine evaluates operational = daily demand x storage days; usable = operational x (1+contingency); gross = usable / (1-unusable). It begins by multiply daily demand by storage duration., then apply contingency to usable storage., and finally gross up for the entered unusable storage allowance. This keeps the calculation auditable instead of hiding design assumptions behind a single number.
operational = daily demand x storage days; usable = operational x (1+contingency); gross = usable / (1-unusable)ToolLott evaluates the relationship using the entered units and full numeric precision before display rounding.
| Symbol / input | Meaning | Unit |
|---|---|---|
dailyDemand | Average daily demand (m3/day) | user input |
storageDays | Storage duration (days) | user input |
contingency | Contingency / reserve (%) | user input |
unusable | Unusable volume allowance (%) | user input |
Step-by-step method
- Multiply daily demand by storage duration.
- Apply contingency to usable storage.
- Gross up for the entered unusable storage allowance.
Worked example
Priya, a project engineer, needs two days of storage for a site consuming 85 m³/day and wants a base operational volume before fire/emergency reserves.
Example inputs
- Average daily demand (m3/day): 85
- Storage duration (days): 2
- Contingency / reserve (%): 0
- Unusable volume allowance (%): 0
Calculation / processing
Operational storage = 85 x 2 = 170 m³.With 0% contingency, usable storage remains 170 m³.With 0% unusable allowance, gross capacity is 170 m³.
Use the result as a screening or quantity-planning value and compare it with the project criteria, manufacturer data and applicable engineering requirements before making a design or procurement decision.
Assumptions
- The entered values are representative of the condition being screened and use the units shown on the page.
- The equation models only the stated relationship; omitted system effects are not silently estimated.
Limitations
- This page is not engineering certification and does not replace applicable standards, design loads, manufacturer data, site investigation or competent professional review.
- Results can change materially when real geometry, losses, transients, material properties, duty cycles, safety factors or regulatory criteria differ from the simplified inputs.
Common questions
Is this a final engineering design?
No. It is a transparent screening calculation using the entered assumptions and the stated equation.
Why does the page show assumptions and limitations?
Engineering formulas are only valid within their modelling assumptions; exposing them helps users decide what additional design checks are required.
Should I use the rounded displayed value in later design work?
Use suitable calculation precision and the governing project/standard requirements rather than relying on display rounding alone.
Methodology sources
Related ToolLott tools
A realistic way Priya could use this tool
Priya is a project engineer.
Priya needs two days of storage for a site consuming 85 m³/day and wants a base operational volume before fire/emergency reserves.
The worked data is explicit: daily demand = 85; storage days = 2; contingency = 0; unusable = 0. From that input set the tool returns Operational storage: 170 m3, so Priya can change one assumption at a time and see what actually drives the output.
The case ends with a measurable/checkable result—Operational storage: 170 m3. That is the evidence Priya can use to two days of storage for a site consuming 85 m³/day and wants a base operational volume before fire/emergency reserves, rather than simply being told the tool was helpful. The page also keeps this limitation explicit: Preliminary screening/planning calculation only.
Fictional scenario using realistic example data. For Ready tools, the worked result is tied to the tested example shown in the tool. Replace the figures with your own inputs and independently verify important professional, financial, legal, health or safety decisions.
What this calculator is for
Use it to estimate operational storage from daily demand and storage duration, then show explicit contingency and unusable-volume allowances.
It sits within ToolLott’s Hydraulic collection, where you can also calculate NPSH, pipe friction loss, pipe velocity, pump head, pump power, reservoir capacity and water-hammer screening values.