How to Choose the Correct Pipe Size

How to Choose the Correct Pipe Size pipe size is important for pumping efficiency

How to Choose the Correct Pipe Size

A common mistake many pond and waterfall builders make is using too small of a pipe for the flow rate of their pump. Always use the same size pipe, or even larger as the discharge port on the pumps. Example: A pump with a 1 1/2″ discharge would need a minimum 1 1/2″ pipe or even 2″.

The correct pipe size is critical in maximizing your pump’s efficiency. Small pipe adds more friction – higher resistance – to the water flowing through it. Higher resistance equates to high higher head. This means that the more resistance, or head that the pipe places on the pump – the less water the pump will pump.

     Maximum Recommended Flow Rates For PVC Pipe

Pipe Size

Gallons Per Hour (GPH)
Gallons Per Minute (GPM)
1/2"
480
8
3/4"
900
15
1"
1,500
25
1 1/4"
2,700
45
1 1/2"
3,600
60
2"
5,400
90
3"
13,500
225
4"
21,000
350
6"
42,000
700

Head Loss (in feet) per 10 Feet of PVC Pipe

GPH
1"
1¼"
1½"
2"
3"
4"
6"
1,200
2.18
.56
.26
.08
1,800
1.19
.55
.16
.02
2,400
2.02
.94
.28
.04
3,000
1.05
.43
.07
.01
3,600
2.0
.58
.09
.03
4,200
.78
.11
.03
4,800
.99
.14
.04
5,400
1.24
.18
.05
6,000
1.50
.22
.06
.01
7,500
.33
.10
.01
9,000
.46
.13
.02
10,500
.62
.18
.02
12,000
.79
.21
.03

Miss Russell Knows Correct Pipe Size its important for pumping efficiency


Head pressure is most often calculated in terms of actual vertical lift – the height water is being lifted. But, for a complete and accurate measurement of Total Dynamic Head Pressure, we have to also add in the Head Pressure, or Loss created by the pipe itself. As water passes through pipe, friction reduces flow rate. The diameter and length of pipe can have a significant affect on the Total Dynamic Head Pressure.

To calculate Total Dynamic Head, add the Head (vertical lift) AND the horizontal Head Loss of the pipe diameter and length of the run.

For example, a 5,400 gph pump pushing water with vertical lift of 6 feet and a distance run of 75 feet would have a Total Dynamic Head of 15.30 Feet with 2" pipe, but would only have 7.35 Feet of Head with 3" pipe.



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