I need to find out how far away a 1.5HP bore pump deliver water without losing to much pressure at the moment it gives about 120 ltrs per min at the top of the bore hole and the furthest I need to get it is about 400 mtrs away

Here's the Short answer followed by the exact Solution.

Use not less than 2" Pipe

Now for the Exact Solution;

Download my Irrigation Calculator from this link

Plug in the information required in the Yellow Color Cells.

Couple more pieces of information needed.

You know Volume Flow is 120 lpm,

put that in Cell D11

You know your Length of Pipeline is 400 meters

Put that in Cell D24

Water Level below Pump while pumping

Elevation difference between Pump and Destination

Add those two and put in Cell D25

What is your electricity rate?

Put that in Cell D50

How many hours per year will you run?

Put that in Cell D51

The answers then come out in the Blue Cells

If you run a lot, you need 3" Pipe

If you run only a little then 2"

If you have any further questions,

Here I am.

Watersedge thanks for the chart it shows me that I might be OK with a 1.5 HP pump but it might be a bit small I have another bore hole with a smaller pump in it is it OK to run 2 pumps into the same system but with different HP

Yes, That's OK

If you can run one pump more hours it's best.

Details almost always matter.

The general concept is allowable but some careful thought is necessary for good efficiency.

Ideally the two pumps are of similar pressure capability,

and are located at similar elevation.

Otherwise there will be increasing mismatch

Each pump has a performance curve peak.

Operating off that peak is a waste of energy, just as line friction is.

It's possible that one pump could run at it's peak pressure, but pump very little water, and therefore just waste electricity.

If it's any comfort, the amount of electricity wasted

spinning on idle against excessive line pressure,

would not be as much as would be consumed under full volume load.

You will know that a pump is not moving water if the case is hot....

the water isn't passing through,

so just sits there and absorbs heat of friction as the pump spins.

For any irrigation system you need to take all those spreadsheet parameters into calculation.

As you complicate the system beyond bare bones, you also have to deal with consequence.