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The Words That Decide the Device
Nobody chooses a backflow assembly by preference. It follows from a classification, and the classification is where the argument actually is.
Key point
The device follows from the hazard classification, which makes the classification the decision. High hazard covers toxic or disease-causing substances and calls for reduced pressure protection; low hazard calls for a double check valve. EPA also separates a pollutant, which causes illness, from a contaminant.
Source: U.S. EPA, Cross-Connection Control Manual, EPA 816-R-03-002, February 2003.
Pollutant and contaminant
The manual separates a pollutant — a substance from a non-potable source that causes illness — from a contaminant, meaning any undesirable substance that degrades water quality.
It is not a pedantic distinction. One is about harm and the other is about quality, and they lead to different protection requirements.
Source: U.S. EPA, Cross-Connection Control Manual, EPA 816-R-03-002, February 2003.
High hazard
Installations involving toxic or disease-causing substances. The manual’s examples are the ones you would expect: plating plants, funeral homes. These call for reduced pressure principle protection.
The category is about what could enter the water, not about how likely anybody thinks it is. A connection that would be catastrophic once is high hazard even if it has never happened.
Low hazard
Connections where the contamination risk is minimal — the manual gives apartment buildings and food processing as examples — and where a double check valve assembly is the usual answer.
Low hazard does not mean no protection. It means a different family of protection.
Why the classification is where to look
Because the device is downstream of it. If you disagree with a requirement you have been given, the disagreement is almost never about the hardware; it is about how the connection was classified and by whom.
That is a conversation with the purveyor and the plumbing official, with the ordinance in front of you, and it is a conversation worth having properly rather than through a contractor.
And which way to be wrong
If you are going to be wrong, be wrong toward the higher classification. Every case history in the manual is an installation that was treated as less hazardous than it turned out to be, usually because nobody imagined the particular event that occurred.
Know what is on the tag before you call.Make, model, size and the date of the last test are usually stamped or tagged on the assembly itself, and they decide which test kit and which paperwork the visit needs. We will route you to somebody who covers your area, selected on the ZIP code of the property, and you are never charged. Backflow is our specialty, though the number will take any plumbing request on the property.
Call (888) 764-9890