Home › What Has Actually Come Back Along a Water Main

What Has Actually Come Back Along a Water Main

EPA’s manual carries case histories rather than warnings. These three are on this page because each demonstrates a different mechanism.

Key point

EPA’s manual records actual incidents rather than warnings: a funeral home aspirator drawing body fluids into a potable supply, sodium hydroxide backsiphoned during a main break with water measured at a pH as high as 13, and about 2,000 cubic feet of propane forced into an eight-inch water main.

Source: U.S. EPA, Cross-Connection Control Manual, EPA 816-R-03-002, February 2003.

CrossConnect is a referral service, not a contractor. We connect property owners and managers with independent contractors. Backflow assembly testing is normally restricted to testers holding a specific certification and using calibrated equipment, and the report usually has to reach your water purveyor — ask to see the certification and ask who files the report. We carry out no testing, we certify nobody, we do not set prices, and we never charge callers anything. Nothing here selects a device for any installation or states that any assembly is passing.

The funeral home

A hydraulic aspirator at a sink created a direct cross-connection. When water pressure dropped, body fluids that should have been flowing into the sanitary drain were instead drawn in the opposite direction, into the potable water supply.

The mechanism is backsiphonage and the connection was a piece of ordinary equipment doing its intended job. Nothing was broken.

Source: U.S. EPA, Cross-Connection Control Manual, EPA 816-R-03-002, February 2003.

Sodium hydroxide, and a main break

A bulk tanker was being unloaded at a chemical company while a water main broke nearby. The driver was withdrawing from the bottom of the tank rather than the top. Sodium hydroxide backsiphoned into the main, and residents were chemically burned. Water was measured at a pH as high as 13.

Two ordinary things — an unloading operation and a main break — that were harmless separately.

Propane in an eight-inch main

A propane tank was being purged using water from private fire hydrants. The gas was at 85 to 90 psi; the water was at 65 to 70. Approximately 2,000 cubic feet of propane flowed into an 8-inch water main. There were explosions in homes and hundreds of residents were evacuated.

85–90 psi against 65–70 psithe pressure difference that put roughly 2,000 cubic feet of propane into a public water main

This one is pure backpressure, and the numbers are the whole story: gas at a higher pressure than the water it was connected to, and water flows from high pressure to low.

What the three have in common

None involved a broken device, because in each case there was no device. None involved anybody behaving unusually. In each, two normal situations coincided and a connection that had been harmless for years was, for a few minutes, a pipe running the wrong way.

That is the argument for protection at connections that have never caused a problem, and it is a better argument than any general warning.

Why they are on this site

Because this trade is usually sold as a compliance obligation, and compliance obligations are easy to resent. These are the reason the obligation exists, and they are published, specific and checkable rather than being a sales story.

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