Population by Freeman's Formula given Quantity of Water Calculator

Freeman's Formula:

\[ P = 5 \times \left(\frac{Q}{1136} - 10\right) \]

Population (in thousands):

Population with Margin (in thousands):

1. What is Freeman's Formula for Population Estimation?

Definition: Freeman's formula estimates population based on the quantity of water required for firefighting in liters per minute.

Purpose: It helps urban planners and civil engineers determine population size for water supply system design.

2. How Does the Calculator Work?

The calculator uses Freeman's formula:

\[ P = 5 \times \left(\frac{Q}{1136} - 10\right) \]

Where:

\( P \) — Population (in thousands)
\( Q \) — Quantity of water (liters per minute)

Explanation: The formula relates water demand for fire protection to population size, with a built-in safety factor.

3. Importance of Population Estimation

Details: Accurate population estimation ensures proper water supply system design, adequate fire protection, and infrastructure planning.

4. Using the Calculator

Tips: Enter the water quantity in liters per minute and safety margin percentage (default ±5%). Water quantity must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why 1136 in the formula?
A: This constant represents the base water requirement per capita for fire protection in Freeman's empirical formula.

Q2: What's the purpose of the safety margin?
A: The margin accounts for uncertainties and variations in water demand (typically ±5%).

Q3: How accurate is Freeman's formula?
A: It provides rough estimates suitable for planning but may need adjustment for specific local conditions.

Q4: When was Freeman's formula developed?
A: It was developed in the early 20th century for American municipal water systems.

Q5: Does this include domestic water needs?
A: No, this calculates only fire protection needs. Total water supply should include domestic and industrial demands.