Potable Water Supply Calculator

Inputs

Example data table

Use the form to match your project conditions and export a report.

Formula used

Recommendations round storage up to the nearest 500 L for practical procurement.

How to use this calculator

1. Enter the expected daily site headcount and a per-person water allowance.
2. Add daily liters for washdown, curing, dust control, and other tasks.
3. Set a peak factor to reflect high-use days and simultaneous consumption.
4. Choose storage days based on delivery reliability and shutdown tolerance.
5. Apply loss and safety percentages to cover leaks and uncertainty.
6. Enter supply hours and optional source flow to check refill feasibility.
7. Click Calculate and download the CSV or PDF for records.

Project article

1) Why potable water planning matters

Potable water is a production input on construction sites. Crews need drinking, handwashing, and hygiene support to maintain output and reduce heat and fatigue impacts. A clear estimate also prevents under-sized storage that triggers stoppages and costly emergency deliveries.

2) Typical per-person allowances

Allowances vary by climate, shift length, and site rules. Many projects start around 40–70 L per person per day for drinking and sanitation. Hot weather and long shifts push values higher. Set a baseline and revise as headcount and working conditions change.

3) Adding task-based water uses

Activities can exceed crew demand. Common contributors include equipment washdown, concrete curing, dust suppression, and temporary cleaning. Enter these as liters per day to keep the estimate transparent. Example: washdown 300 L/day plus curing 200 L/day adds 500 L/day regardless of headcount.

4) Losses and safety factors

Hose runs, flushing, minor leaks, and handling waste create losses that are easy to overlook. A 10% loss factor on a 5,000 L/day base adds 500 L/day. Safety factor covers uncertainty and scope growth; 10% adds another 500 L/day before storage sizing.

5) Peak factor for high-demand days

Peak factor represents days when consumption is higher than average, often due to concurrent trades, hot conditions, or intensive cleaning. A peak factor of 1.5 turns a 5,000 L/day base into 7,500 L/day before losses and safety. Use it for spikes, not unreliable deliveries.

6) Storage days and tank sizing

Storage days define how long you can operate without refilling. If adjusted average demand is 6,000 L/day and storage days are 2, required storage is 12,000 L plus any reserve. Rounding to practical increments supports procurement and comparison between 1,000 L IBCs and larger tanks.

7) Refill windows and required flow

Refill flow ties daily demand to the hours your source is available. If adjusted average demand is 6,000 L/day and supply hours are 6, needed refill flow is 6,000 ÷ (6×60) = 16.67 L/min. Enter source flow to see fill time and utilization.

8) Using outputs for scheduling and bidding

Use adjusted average demand for routine delivery planning and peak demand for stress checks. Storage volume supports tank rental, delivery frequency, and site layout decisions. Export CSV for job files and PDF for submittals, daily logs, and tender attachments. Recalculate after major workforce or phase changes. These numbers help align welfare compliance with daily production targets.

FAQs

1) What does “per person demand” represent?

It is the daily potable water allowance per worker for drinking and hygiene. Choose a value that matches your welfare rules, climate, and shift length.

2) Should I include curing and dust control as potable water?

Only if your project uses potable sources for those tasks. If non-potable water is permitted, enter those liters as zero here and size a separate non-potable system.

3) How do losses differ from the safety factor?

Losses cover predictable waste like flushing and small leaks. Safety factor covers uncertainty, scope growth, and undercounted trades. Using both keeps estimates realistic and resilient.

4) When should I increase storage days?

Increase storage days when deliveries are uncertain, access is restricted, or shutdown tolerance is low. Storage days manage reliability; peak factor manages short demand spikes.

5) Why does the tool show a refill flow rate?

Refill flow indicates how much water per minute you must add during available supply hours to meet average daily demand. It helps confirm whether a mains line or tanker can keep up.

6) What if my source flow is lower than the required flow?

Extend supply hours, increase storage, reduce potable task loads, or arrange supplemental delivery. If utilization is high, plan redundancy to avoid running out during peak periods.

7) How should I use the recommended tank size output?

Use it as a procurement starting point. Compare IBC counts and standard tank sizes, then adjust for site footprint, delivery access, and cleaning and disinfection practices.