How can I measure my casing diameter if I can't remove the cap?

If you can't remove your well cap, there are still reliable ways to determine your casing diameter for pump sizing.

Method 1: Measure the Outside

Circumference Method

Most accurate without cap removal:

1. Wrap a tape measure around the outside of the casing
2. Record the circumference in inches
3. Calculate diameter: Circumference ÷ 3.14 = Outside Diameter
4. Subtract wall thickness (typically 0.2-0.3") for inside diameter

Example:

• Circumference: 14"
• Outside diameter: 14 ÷ 3.14 = 4.46"
• This is likely a 4" casing (4.5" OD standard)

Direct Outside Measurement

Use calipers or careful tape measurement:

1. Measure across the outside of the casing
2. Compare to standard sizes

Standard Casing Dimensions

Method 2: Check the Casing Markings

Printed Information

Many casings have size marked:

• Look for stamped or printed text
• May be near the top
• Clean dirt/debris to see markings
• May include manufacturer and size

Inspection Around Casing

Check the exposed portion:

• Below cap connection
• Above ground level
• May have size stickers or stamps

Method 3: Check Your Records

Property Documents

• Well driller's report
• Home inspection report
• Real estate disclosure
• Previous owner's documents

Contact Well Driller

If you know who drilled the well:

• Company name may be on cap
• May have records on file
• Can verify specifications

County/State Records

Many jurisdictions keep well records:

• County health department
• State geological survey
• Water resources agency

Method 4: Compare to Common Caps

Standard Well Cap Sizes

If you can measure the cap:

• Caps are sized to fit specific casings
• Measure cap diameter
• Match to casing size

When to Call a Professional

Consider professional measurement if:

• Multiple methods give different results
• Well is very old or unusual
• Cap is corroded or damaged
• You're unsure of accuracy

A well service company can:

• Inspect well condition
• Measure accurately
• Video interior if needed
• Verify compatibility with Simple Pump

Why Casing Size Matters

Clearance Requirements

The Simple Pump drop pipe (1" Schedule 80 PVC) must fit:

• Alongside existing submersible pump
• Within the available space
• With room for installation access

Minimum Requirements

• 4" casing: Fits, may be tight with submersible
• 5"+ casing: Comfortable fit with equipment

Got Your Measurement?

Once you know your casing diameter:

• Request Quote: Get Quote
• Verify Compatibility: Call 877-492-8711 ext. 6
• Learn More: Well Compatibility Chart

Still Unsure?

Contact us with your measurement:

• Circumference measurement
• Outside diameter measurement
• Photos if helpful
• Any visible markings

Technical Support: 877-492-8711 ext. 6

We can help verify the casing size and confirm Simple Pump compatibility.