This article explains the requirements for well caps & covers & well cap or cover venting for drilled wells, well casings, dug wells & well pits.

This article series describes the properties & construction of drilled wells that use a steel well casing, modern drinking water wells.

Well Caps, Covers, & Vents

Here we describe requirements & recommendations for a sanitary, sealed cap or cover on drilled wells, bored wells, and cover requirements for dug wells and well pits.

Water wells require a water-tight cap or cover to prevent contamination from surface runoff or flood waters. But some well caps also require an air vent.

Article Contents

• WELL CASING CAP / TOP LOCATION - implications of ground level & below-ground well casing caps
• WELL CASING CAP VENTS & OTHER WELL VENTS
• WELL VENT REQUIREMENTS & STANDARDS
• WELL CAP REQUIREMENTS for SEALING & SAFETY

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Well Caps to Close & Seal the Top of a Drilled Well

Well Casing Caps May be elevated above ground, at ground level, below ground level but accessible in a well pit, or completely buried and inaccessible without digging.

Modern above-ground well casing top

The page top photo is of a modern well casing, in good condition, extended properly above ground.

The small-diameter pipe parallel to the six-inch steel well casing is an electrical conduit - so we know that for this particular water supply system a submersible water pump is used and it is installed in the well itself.

Well casing cap at ground level

The photo above is of an older drilled-well casing which has been placed with its casing cap right at ground level. We can also see in this photo that there is no air vent on this well cap - and indeed an air vent isn't needed at every sealed well cap or well head.

The top and cap of other drilled wells may be completely buried. Both of these approaches, though widely used, increas the risk of well contamination from surface runoff. We also see that this well cap is not vented.

We cannot see from just the photo how successfully this well casing cover has been sealed against water entry from surface runoff.

Well casing top below ground in a well pit

Other well casing tops may be visible in a below-ground well pit, a construction sometimes used to get the top of the well and pipes connected to it below the frost level in a freezing climate.

In our photo above this is a wet well pit with questionable wiring safety but you can see a vent extending above the top of the well casing top cap - a clue that the owners were having a problem with flooding in this pit.

Watch out: wet well pits with electrical components like those shown here may be unsafe to enter.

Examples of these well tops are at WELL PITS

Buried well casing top cap

Well casing covers on older drilled or bored wells that used a steel casing are often buried several feet below ground. So forgive us if we don't have a photo of what that looks like.

Those well casing caps must also be tightly sealed against water entry from surface runoff or groundwater.

Where the pump is offset from the well or where a submersible pump is used, the opening between the well casing and any pipes or cables which enter the well shall be closed by a watertight seal or "well cap". - California DWR Chapter 10, 2016 cited below

In our sketch below we show the typical construction of a drilled water well in cross section.

A typical drilled well steel casing diameter is 6" (4" in some areas), that the well depth can be considerable (from 50 ft. to 900 ft. or more).

Typically the steel well casing extends down into the bedrock or to a depth at which it can be sealed against unwanted surface water entry.

We discuss the construction of drilled wells

at DRILLED WELLS, STEEL CASINGS.

 The water pipe leaving this well to carry water to the building will be buried below ground, and in freezing climates, below the frost line. A special fitting, the "pitless adapter" is used to seal the passage cut into the round well casing. Details are at PITLESS ADAPTER

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What is the function of a well vent?

1. Well cap/casing vent prevents casing vacuum:
   
   On some water wells the presence of a water tight (and thus air tight ) well casing cap can mean that when the pump is running and drawing down the static head in the well it can create a vacuum that could impede pump operation; The vent lets equalizing air into the casing.
2. Well cap/casing vent allows air to vent out:
   
   The well casing top vent also allows air to exit the well as the water column rises in the well, perhaps assisting in well recovery in some well installations.
3. Well cap/casing vent allows gases to vent out:
   
   A well vent also allows the venting out of any gases that might accumulate in the well bore above the static head; that can be a concern for wells whose water supply includes absorbed methane or other gases.

Below: a closer look at the older compression-style well casing cap removed from the well shown above.

This cap achieved a water tight seal to the interior of the well casing when the cap bolts were tightened to in turn squeeze and expand the thick rubber gasket.

A small diameter hole in the well casing cap (yellow arrow) connected to an air vent elbow on the top of the casing cover (visible in the photo above).

Below: new well cap sealed to the well casing; note that the well driller determined that this well no longer needed an air vent, probably because in the well a snifter valve was eliminated as part of installation of a new internal-bladder type pressure tank in the building served by this well in Two Harbors MN, USA.

See details at

WATER TANK BLADDERS & CAPTIVE AIR

and at

SNIFTER & DRAIN BACK VALVES

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Requirements & Standards for Well Casing Cap Vents

Here's an excerpt from the California DWR well standard

Air Vents. In community water supply wells to minimize the possibility of contamination caused by the creation of a partial vacuum during pumping, a casing vent shall be installed (Figure 7). In addition, to release air trapped in the pump column when the pump is not running, air release vents shall be installed (Figure 7).

Air vents are also recommended for other types of wells except those having jet pump installations requiring positive pressure (which cannot have a vent). - California DWR Chapter 10, 2016 cited below, [Emphasis by underscoring added by editor - InspectApedia.com]

Here is another excerpt from California's Chapter 10 on well construction codes:

Openings.

Openings into the top of the well which are designed to provide access to the well, i.e., for measuring, chlorinating, adding gravel, etc., shall be protected against entrance of surface waters or foreign matter by installation of watertight caps or plugs.

Access openings designed to permit the entrance or egress of air or gas (air or casing vents) shall terminate above the ground and above known flood levels and shall be protected against the entrance of foreign material by installation of down-turned and screened "U" bends (see Figures 6 and 7). All other openings (holes, crevices, cracks, etc.) shall be sealed. - op. cit.

You'll see that the vent must be properly constructed so as to prevent entry of surface runoff, flood waters or other contaminants into the well bore.

• "Water Well Standards", [PDF] California Department of Water Resources, 1416 9th Street, Sacramento CA 95814, Tel: 916-653-5791, DWR Chapter 10, retrieved 2016/06/10, original source: http://www.water.ca.gov/groundwater/well_info_and_other/california_well_standards/wws/wws_combined_sec10.html

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Air Vents on Well Casings

Small diameter air intake vents are needed on air-tight shallow well casings

A competent onsite inspection by a well plumbing expert usually finds additional clues that help accurately identify strange pipes or if necessary, diagnose a problem. That

if the second smaller diameter pipe is indeed connected to your well casing or casing top, as is often the case, it is very likely an air vent.

In shallow wells it was common practice to include a vent line to allow air to enter the well casing during water draw-down in the well, in order to avoid the flow resistance that the above-ground shallow-well pump would encounter if a vacuum was formed in the well casing by the falling water level.

Our well casing top photo (left) includes a red arrow pointing to the NPT pipe thread that marks the location where an air vent tube would have been connected had one been in use on this well.

The two larger-diameter galvanized iron pipes and pipe caps protruding through the center of this well cap would have been used to connect the two lines of a two-line jet pump.

So this is not exactly your case, but our photo shows where the air vent connects at a well casing top.

Shallow well single line jet pumps can pull up water from a maximum of about 25 feet, so you can see that with these less powerful pumps you'd want to relieve the vacuum.

It's also plausible that during hurricane and storm flooding ground around your well may have been so saturated as to temporarily convert your well to function as an artesian well - delivering water on its own.

You can follow the pipe you asked about back to the well to confirm its connection and location and thus its use.

Details about well casing air vent tubes and pipes

Finally, 1" is a bit bigger for a well vent than what I've usually encountered. Often the vent line is a simple flexible copper tube of 1/2" in diameter..

Well casing vent pipes are usually routed to a secure, clean indoor location in order to reduce the chances of well contamination from surface water entry into the casing through the vent.

On occasion we've seen copper tubing break off at the top of a well casing, admitting surface runoff and contaminating the well. We've also found an occasional crimped or clogged vent tube on a well casing.

The result of that problem can be reduced water delivery rate from the well - the jet pump is pulling water against a vacuum.

But on some wells we may find a larger diameter well casing vent pipe installed as a standpipe that looks something like our photo at left

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Safety & Sealing Requirements for Well Caps & Covers

We have explained above that the top of a water well needs to be sealed against surface runoff or flood waters as those waters are not sanitary and would contaminate the well water.

Well construction also requires that all below-ground well openings such at a pitless adapter must also be sealed against the entry of outside water.

But well caps and covers must also be secured to prevent other safety hazards such as the following:

• The well cap must be secured against casual removal 
  
  that would permit tossing of debris, disposal of various chemicals or liquids, or dropping of objects into the well as accidental, criminal, mischievous acts.
  
  In most situations that simply means that the cap can't be lifted off by hand but has fasteners that must be removed: that's enough to prevent a child from opening the well.
• Community wells require additional protection:
  
  Enclosure of Well and Appurtenances.
  
  In community water supply wells, the well and pump shall be located in a locked enclosure to exclude access by unauthorized persons. -California DWR Chapter 10 op. cit.
• Dug wells should have a child-proof cover to prevent a child from climbing into or falling into the well.
  
  See DUG WELLS, by HAND
  and
  See WELL SAFETY WALL & COVER
• Well pits should have a child-proof cover
  
   also to prevent a child from falling or climbing into the well pit. Because the cover of a well pit is often at or close to ground level, the cover should also be strong enough to prevent collapse and injury to someone walking over or standing on it.
  
  Also see WELL PITS

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Property Transfer water Tests for vacant home requires a DEC Registered Well Driller to put on a new well cap?

Property Transfer Tests for vacant home. The New York Erie County Health denial reads Well water failed due to loose cap. It states that I need to hire a New York State Department of Environmental Conservation Registered Well Driller to put a new cap on and then they will proceed to do water test.

Is this a legal requirement to have this kind Specialized Registered person to replace a cap?

The health department inspector will not answer me as to why they did not do the water test. He said the Health department will not talk to me since I am now not the owner—

but I explained to him I paid for the test, my money is held in escrow to pay for septic/well repairs and my sellers contract states I am the one to hire repair person, not the new owner.

My lawyer is not helpful. I don’t know the law. On 2021-08-18 by Darlene

by inspectapedia.com.moderator (mod) - trivial job to tighten a loose well casing cap or even to replace it if needed

@Darlene,

My goodness that does sound extreme. This smells like a case of what I call the OTHER PEOPLE's MONEY PROBLEM - someone feels free to throw huge amounts of someone else's money at a problem, perhaps without any rational thought, for their own personal protection from a minuscule risk.

In New York licensed plumbers and also drilled well construction companies are completely capable of tightening a loose well casing cap - in fact if all that's needed is tightening a few screws or bolts that snug the cap to the casing top, anyone with a screwdriver or an adjustable wrench could do it.

But on the other hand if the well casing is not well above ground and if the cap was found off entirely and / or if the proper kind of cap was not installed in the first place, then the well may not be protected from surface contaminants; in that case it may be that a proper cap needs to be installed.

Call your local well driller, ask them to inspect the casing top and either secure the cap or tell you if a different one is needed.
In NYS any well driller in business has got to be NYS DEC registered.

The Simmons water-tight well casing cap shown below costs about $60. U.S. to which you'll add the cost of a well driller service call.

Wrong size, loose cap on well casing - how do I fix it?

I recently purchased a home with a drilled well. The pump is inside the well itself.

The cap just sort of sits on top. There was a pit dug around it with rotten wood laid flat at ground level, surrounding the well pipe. There was Styrofoam packaging used as insulation...

My question is, what is the best way to cover this back up? The hole goes deep enough to see where the power and piping shoot off to the house. Do I need to build something around this for access if there's a problem, or just fill it with dirt and gravel? On 2021-08-01 by James M

by inspectapedia.com.moderator (mod) - warnings about unsafe well construction: exposed wires, wrong cap: shock or contamination issues

@James M,

Watch out: This looks like an improper and unsafe submersible well pump installation.

I see bare wires, no conduit and not even protective insulation run loose through a rocky ground surface, up into a well casing cap that, if it sits loosely atop the casing, is perhaps the wrong size - too big - thus also not secure against movement, wiring damage, and not able to prevent its removal or contaminants from being dumped down the casing at its top.

You will want at least

- a water-tight well casing top of the right size for your well casing so that it can be secured and sealed

- proper conduit to protect the pump's electrical wires

- a water test to confirm that the water is potable and safe

by James M

@inspectapedia.com.moderator, yeah it's sketchy. The conduit is there when it runs to the house. So your recommendation is:

1. Run conduit down and connect to conduit running from the house to protect the wires.

2. Add some form of insulation. Perhaps like a thermal blanket for hot water heater?

3. Replace cap with proper fitting one

4. Do I fill in or build something to leave a "work space" around the well?

by inspectapedia.com.moderator (mod)

@James M,

RE:

1. Run conduit down and connect to conduit running from the house to protect the wires.

if you use underground feeder at adequate depth you don't need conduit below ground but I'd not expect to see wires exposed like in your case - conductors with no insulation and I prefer to see conduit above ground to protect the wire from damage

2. Add some form of insulation. Perhaps like a thermal blanket for hot water heater?

There is no reason to insulate the casing above ground; the water should be leaving the casing below ground, below the frost line, by a pitless adapter

3. Replace cap with proper fitting one

Yes one that fits and connects both casing and conduit

4. Do I fill in or build something to leave a "work space" around the well?

The casing can be left exposed above ground if wired and capped properly; Don't bury it or it may leak and contaminate your well; it should extend above ground.

by James M

@inspectapedia.com.moderator, Thanks for the great tips!

Can I cover the well head casing cap?

I have a well, and a well head in my front yard, I landscaped bricks around and put in a flower bed, I did cover the well head with plastic , will this give me a problem. Thank you On 2020-05-23 by Cinda

by (mod) - If you are going to bury an above ground well casing cap

Cinda,

Thank you for asking a helpful question.

If you are going to bury an above ground well casing cap (this is NOT recommended), then it's important to first assure that the top is completely sealed against water entry.

Otherwise leaks into the well may contaminate your water supply.

A plastic bag was a clever idea, but not reliable.

Watch out: Also, some well casing caps include an air vent that should not be blocked.

What if there's no visible well cap in my yard?

I just moved in to a residential home that has a drilled well. The as-built shows its location, but there is no visible well cap. Is there such a thing as a subsurface well cap? On 2020-03-12 by Kevin Browne

by (mod)

Yes, the well-cap might be buried - hopefully also sealed against water entry. That's particularly likely in an older home. Modern drilled wells are normally brought above grade; other older wells may have the well head exposed in a well pit that is usually closed by a removable cover.

Take a look at WELL LOCATION, HOW TO FIND

To drive over the well, can I bury the well top and run the vent to a safe location?

My vented submersible well pump well ended up where I need to drive over it. I would like to lower the sealed/vented lid, cover/seal and run a vent to a more convenient above grade location vented and screened. That OK ? - On 2019-03-03 by vic kelly

by (mod) - suggestions for well top protection under a drive

That might work provided your vent piping is of sufficient diameter, slope, is routed with pitch so that it doesn't clog and is protected so that it doesn't get smashed by inadequate protection from vehicle passage.

However keep in mind that it sounds as if you're driving right over the well casing top- the well casing top needs both protection from damage AND ease of future access for maintenance or repair. Don't just pave over it.

If I cover the well with a fake rock does the rock need to be vented?

I just installed an artificial rock to cover my well pipe. My pipe looks exactly like the first photo on the page. Does this artificial rock need to be vented? On 2016-08-24 by Diane A

by (mod) - maybe

Diane if your well casing included a top vent, and if the equipment hasn't been modified to make that vent unnecessary, I'd keep the vent working; that might mean that you need to extend it around your decorative rock.

Also be sure that you don't change the ground height so as to increase the risk of sending surface runoff into the well around the casing cap. On an older well that cap may not be water-fight.

 

What holds up the pipes at the well cap in a 2 pipe system?

What holds up the pipes at the well cap in a 2 pipe system?

On my well a PVC elbow is leaking (4 feet underground).

The elbow is very close to cap and I may need to cut it flush with the cap. Can I pull piping up a couple inches to attach new elbow? On 2016-07-01 by mike cortese

Answer by (mod) -

Mike there are different well cap designs; older compression caps that seal at well casing top by compressing two steel plates against one or more thick rubber gaskets may have had pipes that extended through the cap and were sealed by the gasket. Perhaps that's what you have.

Other fittings screw right into the cap top and can't just be pushed sliding through.

See our complete description at WELL CAPS & COVERS

Use the page bottom CONTACT link to send me some sharp photos and perhaps I can comment further.

Or a PITLESS ADAPTER may send pipes out through the side wall of the well casing. In that case the well piping is suspended from the underside of the in-well pitless adapter fitting.

 

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Continue reading at WELL CASING LEAK REPAIRS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• DRILLED WELLS, STEEL CASINGS - home
• HAND PUMP for WELLS - sanitation & vent covers for wells using a hand-operated pump
• PITLESS ADAPTERS - Definition & use of a pitless adapter at water wells
• WATER ODORS, CAUSE CURE
• WELL CAPS & COVERS - for well casing cap sealing & venting requirements
• WELL CASING LEAK REPAIRS
• WELL CONSTRUCTION & MAINTENANCE - home
• WELL PIPING LEAK DIAGNOSIS - a leak in the water piping anywhere between the well bottom and the building can wreak havoc
• WELL PIPING PITLESS ADAPTER
• WELL PIPING REPAIR
• WELL PIPE RETRIEVAL TOOLS
• WELL PITS - special warnings for properties where the well and well equipment, pump, tank, etc. are outside in a pit
• WELL YIELD IMPROVEMENT - how to improve well water yield - steps to try before drilling a new well

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Questions & answers or comments about steel casing drilled water wells at residential properties.