Well Caps, Covers & Vents Requirements for caps, covers & vents on wells
WELL CAPS & COVERS - CONTENTS: 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. This article explains the requirements for well caps & covers & well cap or cover venting.
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Well Cover & Cap Requirements & Well Cap Venting:
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. 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. We discuss well problem diagnosis, testing, & repair procedures - advice about what to do when things go wrong with the well such as loss of water pressure, not enough water volume, contaminated wells, wells that have smelly water, wells that just run out of water or have a low recovery rate. We describe the parts of a water well and its piping and controls including the pitless adapter.
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.
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.
The photo shown here is of an older drilled-well casing which has been placed with its casing
cap at ground level - increasing 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.
[Click to enlarge any image]
Well casing covers on older drilled or bored wells that used a steel casing are often buried several feet below ground. 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 un-wanted surface water entry.
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
Good question Julian; Here are some reasons that many drilled wells with a sealed casing top or sealed cover require a vent:
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.
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.
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 (SNIFTER & DRAIN BACK VALVES) was eliminated as part of installation of a new internal-bladder type pressure tank (WATER TANK BLADDERS & CAPTIVE AIR) in the building served by this well in Two Harbors MN, USA.
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
Safety 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 varoius chemicals or liquids, or dropping of objects into the well as accidental, criminal, mischevious 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.
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
Continue reading at WELL CONSTRUCTION & MAINTENANCE - home or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Ask a Question or Search InspectApedia
Questions & answers or comments about steel casing drilled water wells at residential properties.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
P.O. Box 130140
789 N. Dixboro Road
Ann Arbor, MI 48105, USA
p +1 734 769 8010
f +1 734 769 0109
Toll Free USA
+1800 NSF MARK
(800 673 6275) Website: http://www.nsf.org/
Access Water Energy, PO Box 2061, Moorabbin, VIC 3189, Australia, Tel: 1300 797 758, email: firstname.lastname@example.org Moorabbin Office: Kingston Trade Centre, 100 Cochranes Rd, Moorabbin, VIC 3189
Australian supplier of: Greywater systems, Solar power to grid packages, Edwards solar systems, Vulcan compact solar systems, water & solar system pumps & controls, and a wide rage of above ground & under ground water storage tanks: concrete, steel, plastic, modular, and bladder storage tanks.
Smart Tank, Installation Instructions [ copy on file as /water/Smart_Tank_Flexcon.pdf ] - , Flexcon Industries, 300 Pond St., Randolph MA 02368, www.flexconind.com, Tel: 800-527-0030 - web search 07/24/2010, original source: http://www.flexconind.com/pdf/st_install.pdf
Typical Shallow Well One Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect_Jet_Pumps.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
Typical Deep Well Two Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
Water Fact Sheet #3, Using Low-Yielding Wells [ copy on file as /water/Low_Yield_Wells_Penn_State.pdf ] - , Penn State College of Agricultural Sciences, Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Crystal Clear Supply provides portable ceramic water filter purifiers and portable reverse osmosis water treatment equipment - see http://www.crystalclearsupply.com/category_s/7.htm
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones