Backflow Preventers for Dummies

backflow preventer for sprinkler system

Here at the Antisocial Network, we think there are some common, everyday repair tasks of which every homeowner should be aware, and – if at all possible – capable of performing. We're talking tasks on the order of changing a furnace filter or replacing the battery in a smoke detector, which we think even your grandmother should be able to perform. There are others that require a little more knowledge, but are in reality still pretty easy. Or they would be pretty easy if some PolySci major and MBA-holder didn't get hold of the instructions. Yes, we're talking about Tom Lutzenberger (again) and, this time, his eHow.com post "How to Fix a Water Backflow Preventer"¹ (since transported to HomeSteady.com)

Lutzenberger, like many people who've written for eHow, probably had to look up just what a "water backflow preventer" might be. We hope he learned that the phrasing is redundant... but never mind that. For his tenth trip to the DotD podium, Tom did his research at irrigation websites and plumbing companies. What he never managed to do was find an image of a backflow preventer (which is why he used a picture of a faucet). The version often associated with home sprinkler systems is shown above. Tom did explain, sort of, why you might need a backflow preventer:

"Preventers also help stop contamination of the water in the line since outside water can't push back into the plumbing. This issue tends to be particularly critical when a house [sic] outside the water line shares the same plumbing as the water line that feeds internal faucets used for drinking and consumption. As a result, repairing a broken preventer should be an immediate task if found in disrepair."

The typo (we assume he meant "hose") and the clumsy wording notwithstanding, Lutzenberger was right about the purpose and the necessity of quick repairs. Where he got wonky was in his instructions, which he appears to have cribbed... errr, copied, reworded, and pasted... from a commercial plumbing site. That means he ended up with instructions like Locate the shut-off valve on the unit and the test cock valve. Reference the unit design manual or the Internet for the exact valve location, depending on your valve type and make. Attach a water pressure tool to the line on which the valve is installed. Turn the water on so that the tool registers the water pressure...

...which, frankly are both beyond the capability and beyond the needs of the everyday homeowner. That's what makes his next step so funny:

"Use a wrench to disconnect the backflow preventer from your external water line. Twist it loose until it separates from the spigot going out of the house line. Throw the old unit away. Purchase a new backflow preventer and install it, tightening it back onto the water line with the wrench. Reconnect your external line to the new backflow preventer unit..."

Which is perfectly fine advice if you have a small vacuum breaker like the one shown at left, but is definitely not on-point for the irrigation unit shown above. That's not to mention that there is an entire family of faucets with built-in vacuum breaker/backflow preventer units that can be repaired instead of thrown away.
No, Lutzenberger started by addressing commercial systems, then segued to cheap faucet-mounted units. He never actually addressed the backflow preventer on a sprinkler system, nor did he mention the widely-available hydrants with built-in backflow preventers. Is it any wonder we think he deserves his tenth Dumbass of the Day award?

¹ The original has been deleted by Leaf Group, but can still be accessed using the Wayback machine at archive.org. Its URL was   ehow.com/how_11385044_fix-water-backflow-preventer.html

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