Understanding Water Pressure
Learn how water pressure works between your farm pump and tank
What is Water Pressure?
Water pressure is the force that pushes water from your pump to your tank, usually measured in PSI (pounds per square inch), Kilopascals (kPa), or Bars. Understanding your water pressure helps you monitor your pump's performance and detect issues early.
💡 Quick Reference
10 meters water elevation = 14.5 PSI = 100 kPa = 1 bar
Typical farm pump pressure: 30-70 PSI
How Pressure Changes Between Pump and Tank
Water pressure can vary depending on many things, for example whether your pump is running, water is draining out, or how high your tank sits. Understanding some of these changes can help you interpret your sensor readings.
Elevation and Your Pump
Your pump needs to push water uphill to your tank. For every 10 meters (33 feet) of elevation, your pump needs about 14 PSI of pressure just to overcome gravity.
Example 1: Open/closed Pump 30 Meters Below Tank
Your pump pushes water 30 meters (100 feet) uphill to fill your tank.
Additional pressure for flow: 20 PSI
Pump pressure when the tank ball cock is fully open: 45 PSI
Pump pressure when the tank ball cock is closed: 65 PSI
Tank feed pressure when the tank ball cock is fully open: ~ 0 psi
Tank feed pressure when the tank ball cock is fully closed: ~ 20 psi
Example 2: Monitoring Pump Cycles
Sensor installed on the fill line near your pump, which fills a tank 10 meters (~15 PSI) higher. The pump cuts off at 45 PSI.
Tank full, ball cock closed: ~30 PSI (pump cut-off pressure minus elevation)
Tank empty, ball cock open: ~0 PSI (no resistance)
Pump ON - Tank filling:
Start of fill: ~0 PSI (ball cock fully open, water flowing freely)
As tank fills: pressure gradually increases from 0 to 30
Tank nearly full: ~30 PSI (ball cock closing, restricting flow)
Pump stops when ball cock fully closes and tank is full.
What this tells you: As the tank fills and the ball cock closes, it restricts flow and causes pump pressure to increase. When pressure reaches maximum (ball cock fully closed), the pump stops. The static pressure you see is the pump's cut-off pressure (~60 PSI) minus the elevation (~30 PSI for 20m), giving you ~30 PSI.
Example 3: Understanding the Pressure Gap (Hysteresis)
Your pump doesn't turn back on immediately after it stops - there's a pressure gap to prevent it cycling on and off constantly.
Pump stops at: 60 PSI (tank full, ball cock closed)
Static pressure: ~30 PSI (60 minus 30 for elevation)
As ball cock opens (stock drinking, water leak): pressure starts to drop
Pump starts again at: ~20 PSI
The gap between stop and start is the "hysteresis"
This prevents the pump turning on/off too often.
What this tells you: After the pump stops, you'll see pressure slowly drop as cattle drink and the ball cock opens. The pump won't restart until pressure drops low enough. This gap is normal and protects your pump from excessive cycling. If you see the pump cycling frequently with a small pressure gap, you might have an issue with your pump's bladder or switch.
Reading Your Pump Pressure
Normal Patterns
- Pump starts: Pressure starts to rise as pump turns on
- Pressure gradually increases while pumping: Tank filling, ball cock closing
- Pressure reaches peak: Ball cock fully closed, tank full
- Pressure drops when pump stops: Back to static pressure from full tank
- Gradual pressure drop: Normal as stock drink water
- Pump restarts at lower pressure: Normal pressure gap (hysteresis) to prevent excessive cycling
Warning Signs
⚠️ Watch For These Patterns
- Pump cycling on and off frequently: May indicate a leak
- Pressure lower than usual while pumping: Pump losing power or pipe blockage
- Pressure dropping fast after pump stops: Significant leak
- No pressure at all: Pump failure or water source empty
Where to Place Your Sensor
We suggest placing the sensor near the tank. This is good for monitoring tank fills, and tanks are typically high with good cell coverage and sun for the solar panel.Monitor your system for a few days to view your "normal" pressure patterns. This baseline helps you quickly identify when something changes. Most issues show up as changes in these patterns before they become serious problems, and a person's eye is often better at spotting changes than automated alerts.