Calcady™

Sump Pump TDH

Calculate Total Dynamic Head (TDH) for sump pump selection, accounting for static lift and friction loss.
feet

Total Dynamic Head (TDH)

TDH is the sum of Static Head (the vertical height you are lifting the water) andDynamic Head (the friction created as water rubs against the inside of the pipe). If you use a pipe that is too small, the dynamic head will be so high that the pump won't be able to move any water at all.

Calculated result for Total Dynamic Head:

Total Dynamic Head

11.6 ft
Incl. 1.6ft friction
Calculated result for Recommended Pump:

Recommended Pump

1/3 HP
Based on TDH calculation
For estimation purposes only. Always consult a licensed professional before beginning work. Full Trade Safety Notice →
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What is Sump Pump TDH?

Total Dynamic Head tells you the total resistance a pump must overcome. If you only look at vertical height, you'll ignore the massive friction created by pipe walls and elbows.

Mathematical Foundation

Total Dynamic Head
TDH=Hstatic+HfrictionTDH = H_{static} + H_{friction}
HstaticH_{static}= Vertical Lift (Static Head)
HfrictionH_{friction}= Friction Loss from Pipe/Fittings

Laws & Principles

  • Hazen-Williams friction factors are calculated at a standard 50 GPM flow.
  • A 90-degree 2-inch elbow adds as much friction as 5 feet of straight pipe.
  • Check valves are high-friction points, adding roughly 10 feet of equivalent length.
  • Smaller pipes (1.5") create significantly more friction than larger pipes (3").
  • Always consult the manufacturer's Pump Curve once you have your TDH.

Step-by-Step Example Walkthrough

" 10ft lift through 25ft of 2" pipe with 3 elbows and 1 check valve. "

  1. 1. Static Head = 10 feet.
  2. 2. Calc Equivalent Length: 25ft + (3 elbows * 5ft) + (1 valve * 10ft) = 50ft.
  3. 3. Calc Friction Loss (2" @ 50 GPM = 2.5ft/100ft): (50 / 100) * 2.5 = 1.25 feet.
  4. 4. Total TDH: 10 + 1.25 = 11.25 feet.
Final Result: 11.25 ft TDH required.

Quick Answer: What does the Sump Pump Total Dynamic Head (TDH) Calculator do?

The Sump Pump Total Dynamic Head (TDH) Calculator determines required pump discharge pressure in feet of head by combining static elevation lift, pipe friction losses via Hazen-Williams, and fitting losses (check valves, 90° elbows) per SSPMA guidelines.

How to Use the Calculator

  1. 1.Enter your project parameters into the input fields above. All fields indicate expected measurement units.
  2. 2.Results calculate instantly as you adjust values — no submit button needed.
  3. 3.Use the Share button or export a PDF report to document your calculations.
  4. 4.Review the Knowledge Hub above for governing engineering standards, mathematical formulas, and worked examples.

Pro Tips

Best Practices

  • ✓Double-check input units: Confirm all dimensions match the expected unit (inches, feet, PSI, GPM, etc.) before finalizing designs.
  • ✓Factor in safety allowances: Always apply appropriate engineering service factors or code safety margins above theoretical minimums.

Common Mistakes

  • ✗Don't overlook local code amendments: Local municipal authority having jurisdiction (AHJ) codes may supersede national baseline standards.
  • ✗Don't ignore boundary conditions: Verify operating temperatures, pressures, and load limits do not exceed safe component thresholds.

Frequently Asked Questions

What constitutes Total Dynamic Head (TDH) in a sump pump discharge line?

TDH = Static Head (vertical lift from sump pit water level to highest discharge point) + Friction Head Loss in piping + Equivalent fitting losses through valves and elbows.

Why is an oversized sump pump just as problematic as an undersized pump?

An oversized pump empties the basin too quickly, causing rapid cycling (motor starting and stopping frequently), which overheats the motor switch and drastically shortens pump life.

What is the equivalent friction length of a standard 1.5-inch swing check valve?

A standard 1.5-inch swing check valve creates friction head loss equivalent to approximately 13 to 14 linear feet of straight Schedule 40 PVC pipe.

How does operating point intersect the pump manufacturer performance curve?

The pump operates where the system TDH curve intersects the pump head-capacity curve. If actual TDH is 15 feet, the pump will discharge whatever GPM the manufacturer curve indicates at 15 ft of head.

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