Well Pump Calculator

Well Pump Sizing & Energy Cost Calculator

1 inch 1.25 inches 1.5 inches 2 inches

Calculation Results:

Static Head: 0 feet

Pressure Head: 0 feet

Estimated Friction Loss: 0 feet

Total Dynamic Head (TDH): 0 feet

Estimated Required Pump Horsepower (HP): 0 HP

Estimated Annual Energy Consumption: 0 kWh

Estimated Annual Energy Cost: $0.00

Understanding Your Well Pump Needs

Choosing the right well pump is crucial for ensuring a reliable and efficient water supply to your home or property. An undersized pump might struggle to meet demand, while an oversized pump wastes energy and can lead to premature wear. This calculator helps you estimate the key parameters needed for proper well pump selection and provides an insight into potential operating costs.

Key Terms Explained:

  • Well Depth: This is the total depth of your well, from the ground surface to the bottom. It's a primary factor in determining how much vertical lift your pump needs to achieve.
  • Elevation Difference (Well Head to Highest Faucet): This accounts for any vertical rise from where the pump sits (or the well head) to the highest point water needs to reach in your system. For example, if your well is at a lower elevation than your house, this adds to the total lift requirement.
  • Desired System Pressure (PSI): This is the water pressure you want to maintain in your household plumbing system, typically measured in Pounds per Square Inch (PSI). Common residential pressures range from 40-60 PSI.
  • Desired Flow Rate (GPM): Gallons Per Minute (GPM) is the volume of water you need the pump to deliver. This depends on your household size and water usage habits (e.g., simultaneous showers, irrigation). A typical residential flow rate might be 8-12 GPM.
  • Total Pipe Length (Pump to House): This is the total horizontal and vertical length of the pipe from your pump (or well head) to your pressure tank or the point of entry into your home. Longer pipes increase friction loss.
  • Pipe Diameter (inches): The internal diameter of your water pipe. Larger diameters generally result in less friction loss for the same flow rate.
  • Estimated Daily Water Usage (Gallons): Your average daily water consumption. This helps estimate how long your pump will run each day, which is crucial for energy cost calculations.
  • Electricity Cost (per kWh): The cost of electricity in your area, typically found on your utility bill.
  • Pump Efficiency (%): The efficiency of the pump, representing how much of the electrical energy is converted into useful hydraulic energy. A higher percentage means a more efficient pump. Typical submersible pump efficiencies range from 60-85%.

Understanding the Results:

  • Static Head: The vertical distance water must be lifted from the well's water level to the ground surface, plus any elevation difference to the highest point of use.
  • Pressure Head: The equivalent vertical height of water needed to achieve your desired system pressure. (1 PSI ≈ 2.31 feet of head).
  • Estimated Friction Loss: The energy lost due to the resistance of water flowing through pipes, fittings, and valves. This increases with flow rate, pipe length, and smaller pipe diameters.
  • Total Dynamic Head (TDH): This is the most critical value for pump sizing. It's the sum of static head, pressure head, and friction loss. It represents the total vertical distance and pressure the pump must overcome.
  • Estimated Required Pump Horsepower (HP): The power output needed from the pump motor to deliver your desired flow rate against the calculated TDH, taking pump efficiency into account.
  • Estimated Annual Energy Consumption (kWh) & Cost ($): These figures provide an estimate of the electricity your pump will consume and the associated cost over a year, based on your daily water usage and local electricity rates.

Important Considerations:

This calculator provides an estimate. For precise pump sizing, it's always recommended to consult with a qualified well driller or pump professional. They can account for specific factors like well recovery rate, water quality, specific pipe materials, and future water demands.

function calculateWellPump() { // Get input values var wellDepth = parseFloat(document.getElementById("wellDepth").value); var elevationDifference = parseFloat(document.getElementById("elevationDifference").value); var desiredSystemPressure = parseFloat(document.getElementById("desiredSystemPressure").value); var desiredFlowRate = parseFloat(document.getElementById("desiredFlowRate").value); var totalPipeLength = parseFloat(document.getElementById("totalPipeLength").value); var pipeDiameter = parseFloat(document.getElementById("pipeDiameter").value); var dailyWaterUsage = parseFloat(document.getElementById("dailyWaterUsage").value); var electricityCost = parseFloat(document.getElementById("electricityCost").value); var pumpEfficiency = parseFloat(document.getElementById("pumpEfficiency").value); // Validate inputs if (isNaN(wellDepth) || wellDepth < 0 || isNaN(elevationDifference) || elevationDifference < 0 || isNaN(desiredSystemPressure) || desiredSystemPressure <= 0 || isNaN(desiredFlowRate) || desiredFlowRate <= 0 || isNaN(totalPipeLength) || totalPipeLength < 0 || isNaN(pipeDiameter) || pipeDiameter <= 0 || isNaN(dailyWaterUsage) || dailyWaterUsage < 0 || isNaN(electricityCost) || electricityCost < 0 || isNaN(pumpEfficiency) || pumpEfficiency 100) { alert("Please enter valid positive numbers for all fields. Pump Efficiency must be between 1 and 100."); return; } // Convert pump efficiency to a decimal var efficiencyDecimal = pumpEfficiency / 100; // 1. Calculate Static Head var staticHead = wellDepth + elevationDifference; // 2. Calculate Pressure Head (1 PSI = 2.31 feet of head) var pressureHead = desiredSystemPressure * 2.31; // 3. Estimate Friction Loss (Simplified approximation for PVC pipe) // Using friction factors per 100 feet for 10 GPM, then scaling by flow rate^1.85 var frictionFactorAt10GPM; if (pipeDiameter === 1) { frictionFactorAt10GPM = 4.5; // ft/100ft for 1″ pipe at 10 GPM } else if (pipeDiameter === 1.25) { frictionFactorAt10GPM = 1.5; // ft/100ft for 1.25″ pipe at 10 GPM } else if (pipeDiameter === 1.5) { frictionFactorAt10GPM = 0.7; // ft/100ft for 1.5″ pipe at 10 GPM } else if (pipeDiameter === 2) { frictionFactorAt10GPM = 0.2; // ft/100ft for 2″ pipe at 10 GPM } else { // Fallback for other diameters, or provide a warning frictionFactorAt10GPM = 1.5; // Default to 1.25″ factor if unknown // console.warn("Using default friction factor for pipe diameter " + pipeDiameter + " inches."); } var frictionLoss = frictionFactorAt10GPM * Math.pow(desiredFlowRate / 10, 1.85) * (totalPipeLength / 100); // 4. Calculate Total Dynamic Head (TDH) var totalDynamicHead = staticHead + pressureHead + frictionLoss; // 5. Calculate Required Pump Horsepower (HP) // Formula: (GPM * TDH) / (3960 * Efficiency) // 3960 is a constant to convert GPM-feet to HP var requiredPumpHP = (desiredFlowRate * totalDynamicHead) / (3960 * efficiencyDecimal); // 6. Calculate Energy Consumption and Cost // Pump run time per day (hours) var pumpRunTimeHoursPerDay = (dailyWaterUsage / desiredFlowRate) / 60; // Daily energy consumption (kWh) // 1 HP = 0.746 kW var dailyEnergyConsumption = (requiredPumpHP * 0.746 * pumpRunTimeHoursPerDay) / efficiencyDecimal; // Annual energy consumption (kWh) var annualEnergyConsumption = dailyEnergyConsumption * 365; // Annual energy cost ($) var annualEnergyCost = annualEnergyConsumption * electricityCost; // Display results document.getElementById("staticHeadResult").innerText = staticHead.toFixed(1); document.getElementById("pressureHeadResult").innerText = pressureHead.toFixed(1); document.getElementById("frictionLossResult").innerText = frictionLoss.toFixed(1); document.getElementById("totalDynamicHeadResult").innerText = totalDynamicHead.toFixed(1); document.getElementById("requiredPumpHPResult").innerText = requiredPumpHP.toFixed(2); document.getElementById("annualEnergyConsumptionResult").innerText = annualEnergyConsumption.toFixed(0); document.getElementById("annualEnergyCostResult").innerText = annualEnergyCost.toFixed(2); } // Run calculation on page load with default values window.onload = calculateWellPump;

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