How to Choose a Well Pump: Complete Selection Guide

Information You Need

Before Selecting a Pump, Know:

1. Well depth: Total depth in feet
2. Static water level: Where water sits (not pumping)
3. Drawdown: How far water drops when pumping
4. Well yield: GPM the well can sustain
5. Casing diameter: 4", 6", etc.
6. Required flow: How many GPM you need
7. Pressure needs: 40/60 PSI typical

Where to Find This Info

• Well log (driller's report)
• Previous pump specifications
• Yield test results
• If unknown: professional assessment

Pump Types

Submersible Pumps

Located underwater in the well.

Best For:

• Wells over 25 feet deep
• Most residential applications
• Deep wells (any depth)

Advantages:

• Quiet (underwater)
• Efficient (pushes, doesn't pull water)
• Self-priming
• Protected from elements
• Long life (10-15+ years)

Disadvantages:

• Harder to service (must pull from well)
• More expensive upfront
• Requires compatible casing size

Jet Pumps - Shallow Well

Located above ground, for shallow applications.

Best For:

• Wells under 25 feet deep
• Water at shallow depth

Advantages:

• Easy to service (above ground)
• Lower cost
• Simple installation

Disadvantages:

• Must stay primed
• Noisy operation
• Limited depth capacity

Jet Pumps - Deep Well

Above ground pump with jet assembly in well.

Best For:

• Wells 25-100 feet
• When submersible isn't an option

Notes:

• Uses two-pipe system
• Less common than submersible
• Easier service than submersible

Quick Comparison

Flow Rate Requirements

Determining GPM Needs

Rule of thumb: 1 GPM per water fixture in home

Typical Fixture Flow:

• Shower: 2-2.5 GPM
• Faucet: 1-2 GPM
• Toilet: 3 GPM (fill)
• Dishwasher: 2 GPM
• Washing machine: 3-4 GPM

Household Size Guidelines:

Don't Exceed Well Yield

• Pump shouldn't pump faster than well produces
• If well yields 8 GPM, use 8 GPM pump
• Oversized pump damages well

Pump Sizing

Calculate Total Dynamic Head (TDH)

TDH determines HP needed.

TDH = Pumping level + Pressure + Friction loss

Components:

• Pumping level: Static level + drawdown + height to tank
• Pressure: PSI × 2.31 = feet of head
• Friction loss: From pipe (use tables)

HP Guidelines (Rough)

Actual sizing requires pump curve analysis

Use Pump Performance Curves

• Each pump has performance curve
• Shows GPM at various head pressures
• Select pump that operates in efficient range
• Don't operate at extremes of curve

Features to Consider

2-Wire vs 3-Wire (Submersible)

• 2-Wire: Control box in motor (in well)
• 3-Wire: Control box above ground
• 3-wire easier to diagnose/repair controls

Motor Type

• Standard induction motor
• Franklin motors (quality standard)
• Variable speed (constant pressure systems)

Construction Materials

• Stainless steel impellers (most common)
• Thermoplastic impellers (budget)
• All stainless (aggressive water)

Casing Size Compatibility

• 4" well needs 4" compatible pump
• Larger casings offer more options
• Check pump diameter vs casing ID

Frequently Asked Questions

How do I know what size well pump I need?

Based on well depth, water level, required GPM, and pressure. Calculate TDH and select pump from performance curves.

Submersible or jet pump?

Submersible for wells over 25 feet. Jet pump for shallow wells. Submersible is standard for most residential wells.

Can I install a pump myself?

Surface jet pump: possible for handy homeowners. Submersible: typically requires professional equipment and knowledge.

How long do well pumps last?

Submersible: 10-15+ years. Jet pump: 8-15 years. Varies by quality, water conditions, and proper sizing.

What if I'm not sure about my well specs?

Have a professional assess your well. They can measure water level, test yield, and recommend proper sizing.