The Complete Backflow Enclosure Guide

What is a backflow cover?

A backflow cover is designed to protect backflow preventers from vandals and the weather. When the weather turns, a backflow cover will keep snow and rain off of your equipment. It can also prevent your backflow preventer from freezing in winter and keep it safe if a tree falls in a windstorm.

Thieves can’t get to your backflow preventer either, as long as it is covered. Your equipment is built with valuable materials like copper and brass that some people try to sell as scrap. A backflow cover also provides you the peace of mind of knowing that someone can’t come by and vandalize your equipment.

A backflow enclosure or backflow cover has a specific job to do. But you may receive a drawing calling out some generic backflow enclosure.  Now you’re likely going to have to research and specify some sort of backflow enclosure solution. As you inquire of colleagues and search online you’ll find plenty of them. Bags, cages, fake rocks, stock aluminum and fiberglass enclosures for common applications like above ground valves, today’s engineer has a wide range of options to consider.

Here it is the complete list of all the different kinds of manufactured backflow enclosures available. Find out all the key information for each type including:

  • levels of protection
  • sizes
  • cosmetic options
  • price ranges

Bags or Blankets

Protection: The R-13 thermal insulation insulated_bag_for_backflow_preventers_only_offer_frost_protection.jpgprovides frost protection to the pipes within the bag, but there is no thief or vandal protection.

Sizes: from 24" x 24" up to 60" x 60"

Colors: green, blue, tan

Prices: $10 to $50

Important to Note: These are typically sold together with a fake rock, cage or plastic cover so they can provide frost protection while the outer cover provides further protection.


Protection: Marine grade aluminum with locking mechanism provides protection from thieves, vandals and accidents. R-9 SafeTCover_industrial_enclosures.jpgpolyisocyanurate insulation provides frost protection. A slab mounted heater provides freeze protection to both the pipes inside the industrial shelter and the riser pipes beneath the slab.

Sizes: almost limitless with standard models from 9" x 26" x 25" to 90" x 174" x 90" with significantly larger custom enclosures built

Colors: typically mill-finish, gray, tan or green with more than 30 options available

Prices: $500-$10,000

Important to Note: The panel design used by some manufacturers makes them easy to customize everything from size and color to climate control to cutouts and additions.

Fake Rock

Protection: Some backflow enclosure models provide freeze protection through the use of a "positive means of heat" and R-8 thermal insulation, others provide frost protection only through thermal insulation and most fake_rock_backflow_enclosures_are_often_wrong_size.jpgdo not provide protection from freezing temperatures. These backflow covers are designed to protect the equipment from thieves and vandals but do not have a locking mechanism. They can be made of plastic or fiberglass depending on the manufacturer.

Sizes: interior size of each rock both varies and tapers

Colors: varying shades of , tan and brown

Prices: $30 to $3,000

Important to Note: Thesegray are typically sold together with an insulated bag so they can provide frost protection. The main appeal for these is that they blend into the landscaping for aesthetic and theft protection purposes. It is important to know the interior dimensions of your model throughout the entire enclosure as they taper and people often buy one then find it to be too small in some areas. They are only for backflow preventer assemblies 2" and smaller.

 Download the enclosure design guide with the top 5 enclosure design  considerations



Protection: These have no insulation at all to provide frost or freeze protection, but do provide some vandal, accident and thief backflow_preventer_cages_have_no_freeze_protection.jpgprotection as they are powder coated steel and do include a locking mechanism.

Sizes: from 24" x 24" up to 60" x 60"

Colors: typically green and tan

Prices: $300 to $1,000

Important to Note: These are only able to be used in situations where the temperatures do not fall below 33° Fahrenheit as they do not provide either frost or freeze protection. They can be used in conjunction with an insulated bag. They are typically only sold for backflow assemblies 2" and smaller.


Protection: Fiberglass shelter with locking mechanism provides protection from thieves, vandals and accidents. Spray fiberglass_valve_enclosures_offer_protection_but_dont_last.jpgfoam insulation provides frost protection and a wall mounted heater can provide freeze protection to the pipes inside the box.

Sizes: one leading manufacturer sells models from 20" x 6.5" x 22" to 83" x 26" x 55"

Colors: beige

Prices: $300 to $6,000

Important to Note: While fiberglass is able to withstand caustic conditions, these covers are susceptible to fiber bloom and cracking because of UV rays. In larger sizes, fiberglass enclosures are comparable in price to aluminum. Most agree that aluminum is superior to fiberglass when the cost is the same.


ProtectionSome backflow enclosure models provide freeze protection through plastic_backflow_enclosures_are_typicall_used_with_an_insulated_bag.jpgthe use of a "positive means of heat" and an insulated bag, others provide frost protection only through the insulated bag and most do not provide protection from freezing temperatures. These backflow covers are designed to protect the equipment from thieves and vandals but do not have a locking mechanism and, of course, are made of plastic.

Sizes: from 34" x 16.5" x 26.5" to 48" x 16.5" x 26.5"

Colors: green and tan

Prices: $200 to $650

Important to Note: These are typically sold together with an insulated bag to provide frost protection. They are designed for backflow preventers 2" and smaller as well as pressure vacuum breakers.

Often, project engineers faced with deadlines give this ancillary component much less attention than the core components of the project. That’s understandable, but you still have to make the right long-term solution. With this list, you should be able to make an expedient and informed decision about your industrial enclosure. Remember, if it's worth protecting, it's worth protecting properly.

Do I need a backflow cover?

Installing a backflow enclosure outside the building in an above-ground enclosure is the best practice and the right thing to do if space on the property is available. You will definitely need one if you are in a cold-weather climate and your backflow preventer is being installed outside the building (where it’s supposed to be). Backflow covers can be heated, which will keep your equipment from freezing. It will also protect it from other elements like wind and rain.

Backflow cages have no insulation to provide frost or freeze protection but do provide some vandal, accident and theft protection as they are powder-coated steel and include a locking mechanism. But your backflow preventer will be safest under a backflow cover.

aluminum enclosure

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