1. What is a Water Pressure Tank Calculator?

Definition: This calculator estimates the required volume of a pressure tank based on the desired drawdown capacity and system pressure factor.

Purpose: It helps plumbers, engineers, and homeowners properly size pressure tanks for water systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( V \) — Required tank volume (gallons)
• \( D \) — Desired drawdown volume (gallons)
• \( P \) — Pressure factor (dimensionless)

Explanation: The drawdown is multiplied by the pressure factor to determine the minimum tank size needed to provide the desired water volume between pump cycles.

3. Importance of Proper Tank Sizing

Details: Correct tank sizing prevents short cycling of pumps, maintains consistent water pressure, and extends equipment life.

4. Using the Calculator

Tips: Enter the required drawdown volume in gallons and the pressure factor (default 0.33 for typical 40/60 psi systems). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is drawdown volume?
A: The amount of water available between pump cycles (from cut-in to cut-out pressure).

Q2: How is pressure factor determined?
A: It's calculated as (P_cut-in × P_cut-out) / (P_cut-out - P_cut-in).

Q3: What's a typical pressure factor?
A: For common 40/60 psi systems, it's 0.33 (20/40 psi = 0.25, 30/50 psi = 0.375).

Q4: How do I find my drawdown requirement?
A: Estimate based on peak demand or use 1 gallon per minute of pump capacity.

Q5: Does this account for bladder tanks?
A: Yes, the calculation works for both bladder-type and conventional pressure tanks.