Well Caps & Well Seals

Built to Seal.
Built to Last.

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Well caps and seals designed for dependable protection, clean installs, and long-term performance.

Well Cap
Well Seal
Well Cap
✓ Built for Water Well Systems
✓ Multiple Sizes & Configurations
✓ Trusted by Installers Nationwide

Turn on the Tap with Confidence

A properly sealed wellhead helps block surface runoff, debris, and insects — protecting your water before issues start.

Why a Proper Seal Matters

  • Surface water and debris collect at ground level
  • Insects and animals look for openings
  • A poor seal creates doubts about sanitation

Common Problems with Others

  • Bugs and debris getting in
  • Cracked caps or worn gaskets
  • Caps that won’t stay sealed
  • Rusted fasteners during maintenance

How Merrill Fixes Common Wellhead Problems

Bugs & debris Vermin-resistant watertight caps + screened venting per strongest well code
Cracks / leaks Durable ABS or cast metal + neoprene gasket / O-rings per quality standards
Won’t stay sealed Compression sealing designed to maintain a tight fit with quality gaskets
Rusted fasteners Stainless hardware on select models or acorn nuts cover threads from outdoor elements

Cap vs. Seal

Most well owners choose a well cap for maximum protection.
But depending on your setup, a well seal can be the simpler option.

Choose a Well Cap if you want:

Well Cap
  • Full protection at the wellhead
    (runoff, debris, bugs, critters)
  • A setup with a pitless of some type
  • The most reliable
    long-term solution
A smart investment in long-term protection that helps reduce the risk of future problems.

Choose a Well Seal if you need:

Well Seal
  • A simple, lower-cost solution
  • A system without a pitless adapter
  • A setup in warmer climates
    with less freezing risk
A straightforward option that’s easier to install and works well for warmer climate.
✓ Cap = more protection
$ Seal = simpler, lower cost

We carry one of the most complete selections of both — so you can get the setup that actually fits your system.

Pick Your Size

Most wells are:

4" 5" 6"

Tip: Match your existing cap/seal or measure the casing.

Choose Material

Metal — Cast Aluminum or Powder Coated Gray Iron

Cast aluminum or gray iron + neoprene O-rings + stainless screen/bolts on select models.

ABS — High Impact Plastic

Hi-impact ABS resin designed for outdoor weatherability.

Customer Reviews

Why Customers Choose Merrill Well Caps & Seals

Real customer feedback on fit, quality, durability, and dependable well protection.

Curtis F.
✓ Verified
6/17/2025
★★★★★
Exactly as described. Perfect fit.
Item type:
6" I.D. 6-5/8" O.D. / 1-1/4" Conduit Tap / 3/4" Vent
John B.
✓ Verified
6/3/2026
★★★★★
It was a high quality part, worked perfectly for my well, I would buy again when I install another well.
Item type:
6" I.D. / 1-1/4" Drop Pipe 1" Cable Tapping / 1/2" Vent
Anonymous U.
✓ Verified
12/31/2022
★★★★★
Worked great and exactly as needed. Strong rubber gasket good metal plate.
Item type:
Well Cap / Seal

Common Questions

Cap or seal — what’s the difference?

Cap covers the casing top for maximum protection. Well seal is simpler and cheaper but offers less protection and complete freeze exposure.

How do I know what size I need?

Match your casing. Most are 4", 5", or 6". Total 4" = 4.5"OD, 5"=5.56"OD, 6"=6.025"OD

Will this help keep bugs and debris out?

A watertight, properly installed cap helps block insects and debris and stops contamination risk.

Do fasteners rust?

Select models include stainless hardware or acorn nuts to cover exposed threads

If I’m unsure, what matters most?

Does your well have a pitless adapter or does pipe from pump come out top of well?

Get the Setup That Actually Fits Your System

View Merrill well caps and well seals built for dependable protection, clean installs, and long-term performance.

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