Plumbing Issues Force Downtown Court to Close Early Thursday
I saw this headline in the LA Times last month, and reading it and the accompanying blurb brought a plumbing issue to mind. What happened was that a drop in water pressure throughout the entire building caused some of the upper floors to have no water at all.
This is the exact scenario that Backflow Preventers were developed for.
A backflow preventer is a device used to prevent water from the user side of the device from flowing back into the supplier side of the device. It has a check valve, or check valves installed in series with a drain line. When the supply or upstream pressure drops to a point lower than the discharge or downstream side, the check valves will close, and the drain line will open so the water rushing back from the discharge side will be diverted form re-entering the supply line.
Initial Reasons for Backflow Prevention
Backflow prevention is obviously important in manufacturing or other industrial plants, because of the uses such facilities have for water. Without backflow prevention, harmful chemicals could be drawn back into the water supply. Industrial plants usually have several backflow preventers installed, because within the plant they don’t want chemicals from one application being inadvertently mixed with chemicals from another. More importantly than that, they don’t want the chemicals being able to work their way back into a building’s domestic, or potable (water used for drinking, cooking, or personal hygiene), water supply. By code, such buildings must have a dedicated domestic water supply that branches off from the main water supply before it goes to any processing applications. There will then be a backflow preventer installed immediately after that branch line to ensure that processed water cannot flow back.
The Expanding Use of Backflow Prevention
Most municipalities now require, by code, that every commercial or public building have backflow preventers installed. You may think, “Why would an apartment house or a courthouse like the one in the headline need backflow preventers installed?”
Let’s say that Joe the Janitor was working on the third floor of the courthouse on the day in question. Let’s further say that he was filling that fine-looking bucket with a hose tied into the faucet of a deep sink, and that the bucket was just about full at the time of the pressure drop. Not really knowing what had happened, Joe threw the hose into the bucket and went to confront Bob the Boiler Guy, because, Joe just knew that Bob was to blame. Joe, having lost all water flow, was so aggravated about the incident that he forgot to shut off the faucet. Without a backflow preventer installed, the pressure drop would have most certainly caused Joe’s hose to syphon the dirty, soapy, mop water from his bucket back into the building’s water supply, potentially contaminating the whole building. Without a backflow preventer at the building’s supply line, the contamination could spread to the water system for the entire neighborhood.
Like most tragedies, the events as I’ve described them would be what author Lemony Snicket would call “A Series of Unfortunate Events.” This scenario, however, is really quite conceivable, and municipal planners must prepare for any and all such circumstances.
Residential Use, Too
Judy, in apartment 5A, while using a shower wand hooked up to her bath faucet, is washing her hair. She loses water pressure and splashes the wand into the bath water while sloshing off to investigate. This causes dozens of gallons of bath water to flow back through the wand and into the entire building’s domestic water supply. Again, city planners and code enforcers nationwide are aware of such possibilities, and have developed their codes accordingly.
What about a Small Apartment House or a Single Family Dwelling?
Many cities and towns now require all multifamily homes to be equipped with backflow prevention. As for a single family home, you should contact your local officials to determine the requirements for your town.
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