WATER is In compressible. FACT

Water moves through inserts as follows. VENTURI EFFECT on water passing through short interruptions like inserts.

Returns to previous speed (volume remains the same) once it has passed narrower section.

Q.So what affects water volume over long run water lines?

A. Turbulence caused by uneven pipe surface constantly dragging & interrupting flow on the outside of the water column.  

Gripmax Hydrodare Alkathene Rural Water Pipes & Fittings.

The Irish Farmers Choice.