Let’s be honest — when someone says “Calculate the Total Dynamic Head”, it can sound more complicated than it really is.

In simple terms:

TDH is the total resistance your pump must overcome to move water from point A to point B.

That resistance comes from:

• Lifting the water (height)
• Creating pressure (if required)
• Overcoming pipe friction
• Pushing through bends, valves, and fittings

If you understand those four things, you understand TDH.

Let’s walk through it step by step — the practical way you would use on a real job.

Step 1: Start With the Flow Rate. Critical for Dynamic Head

Before anything else, ask:

How much water must we move?

Everything — especially friction loss — depends on flow.

Example:

• Flow required = 30 m³/h

If you guess the flow, your TDH will be wrong. Always start here.

Step 2: Calculate the Static Head (The Vertical Lift)

This is simply the height difference.

It does not matter how long the pipe is — only the vertical change.

Ask two questions:

1. How far below (or above) the pump is the water source?
2. How high must the water go on the discharge side?

Example:

• Water level is 2 m below the pump → 2 m suction lift
• Discharge point is 18 m above the pump → 18 m

So:

Static Head = 2 + 18 = 20 m

That’s the “gravity part” of the work.

Step 3: Add Pressure Head (If Required) in Dynamic Head Calc

If the water just flows into an open tank, you can skip this.

But if you need pressure at the outlet — like irrigation, sprinklers, or a pressurised system — you must convert pressure into meters.

Remember:

• 1 bar ≈ 10 meters of head

Example:

• Required outlet pressure = 3 bar
• 3 × 10 = 30 meters

So now we add that.

Step 4: Calculate Pipe Friction (Where Many Mistakes Happen)

Water rubbing against the inside of the pipe causes friction.

Longer pipe + smaller pipe + higher flow = more friction.

To calculate friction, you need:

• Pipe length
• Pipe size (internal diameter)
• Flow rate
• Pipe material

Example:

• 220 meters of pipe
• At your flow, the friction chart shows 3.8 m per 100 m

So:

(220 ÷ 100) × 3.8 = 8.36 m friction loss

That’s resistance the pump must fight.

Step 5: Don’t Forget Fittings and Valves in Dynamic Head Calcs

Bends, non-return valves, foot valves, filters — they all add resistance.

Many installers ignore this… and then blame the pump.

You can estimate minor losses or add equivalent pipe length.

Example:
Minor losses add roughly 2.5 m

Step 6: Now Add Everything Together

Let’s total it:

• Static head = 20 m
• Pressure head = 30 m
• Pipe friction = 8.36 m
• Minor losses = 2.5 m

TDH = 20 + 30 + 8.36 + 2.5

TDH = 60.86 m

Round it to 61 m

That is the total head your pump must deliver at 30 m³/h.

Step 7: Add a Small Safety Margin (Be Sensible)

Real systems change over time:

• Filters clog
• Valves partially close
• Borehole levels drop
• Pipes get extended

Adding 5–10% margin is often wise.

So your design TDH might be closer to 65–68 m.

Why This Really Matters

Most pump problems are not mechanical failures.

They are incorrect TDH calculations.

When TDH is wrong:

• The pump runs off-curve
• The motor overloads
• Energy consumption increases
• The system never performs properly

When TDH is correct:

• The pump operates at its duty point
• Efficiency improves
• Reliability increases
• Everyone is happy

The Simple Way to Remember TDH

Think of it like this:

Your pump must:

1. Lift the water
2. Create the required pressure
3. Overcome pipe friction
4. Push through fittings

Add those together — and you have your TDH.

If you’d like, give me:

• Flow rate
• Pipe size and length
• Suction condition
• Required outlet pressure
• Approximate number of bends and valves

And I’ll calculate a clean, professional TDH example that you can even use for training your sales team.