Pump Systems & Pressure: When You Need One (and How to Size It) — Plain English Guide

McMillan Industries
Jan 29
2 min read

If your sprinklers are dribbling, your drippers barely drip, or your system works great in one zone and terrible in the next, you’re probably dealing with a pressure and flow problem. In irrigation, “pressure” is the push, and “flow” is the volume. You need both for a watering system to perform properly. That’s where pump systems come in.

When you might need a pump

You may need a pump if:

You’re on tank water, a dam, river, or bore (gravity feed usually won’t cut it).
Your mains pressure is low or inconsistent, especially at peak times.
Your yard has long runs, elevation changes, or lots of zones and pressure drops as water travels.
You’re adding irrigation to a property with multiple taps, sheds, or garden beds already drawing from the same supply.
Your system can’t run the number of sprinklers you need without losing coverage.

A quick clue: if your sprinklers produce a weak spray, don’t “throw” far enough, or some heads pop up and others don’t, your pressure/flow is likely under what the system demands.

Pressure vs flow: the common mix-up

Many people assume “more pressure” fixes everything, but irrigation is usually limited by flow. A pump can help by delivering the right combination of flow and pressure to match your system’s requirements.

How to size a pump (simple version)

Sizing starts with two numbers:

Total flow needed (L/min): Add up the flow rates of the sprinklers/drippers in the largest zone that will run at once. (Your installer can measure this or calculate from product specs.)
Total head/pressure needed: This includes:
- The pressure your sprinklers need to operate properly,
- Friction loss from pipe length and fittings,
- Any height difference (watering uphill needs more push).

In plain terms: the more sprinklers you run, the more flow you need. The further you push water (or the higher you lift it), the more pressure you need.

What happens if it’s oversized or undersized?

Undersized pump: weak coverage, constant issues, short pump life from overworking.
Oversized pump: noisy operation, wasted power, higher wear, and potential damage without correct control gear.

The takeaway

A pump isn’t “bigger is better”—it’s “matched is best.” The right pump gives you reliable pressure, even coverage, and a system that runs efficiently for years.

If you’re unsure, Midwest Watering Systems can test your supply, measure your system demand, and recommend the right pump setup—no guesswork, just great watering.