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bbqjoe 05-29-2006 10:18 AM

Group discussion #6 Water backflow & cross connection
This is not so much a food issue as it is a health issue, but it does apply to cooking etc.

This is something that most people wouldn't think about.
In commercial applications it is health code, in some communities it is addressed by building codes.
But either way it is still very easy to contaminate your home or even your communities water supply.
The eaisest way to to do this is by "Cross connection." And I am willing to bet 100% of us are all guilty at one time or another of setting up the potential for it.

Cross connection is when used water is permitted a route to sanitary water.

The simplest and most common method is your garden hose.

Imagine this scenario: You fill up the kids wading pool.
The kids all play in it. The neighbors kids join in. Even the family dog plays with the kids in pool. We now have a nice "Bacteria soup, sitting at optimum temperatures for rapid growth. The garden hose is left dangling over the side into the pool.

Any number of things can now happen, and probably won't, but the possibility is there.

Your foot valve (one way valve) on your well gives up, or maybe the local fire dept. opens a hydrant close by for some reason. Either way a drop in water pressure occurs and creates a vaccumm.
The water in your wading pool is sucked backwards into your home plumbing system, and maybe down into your well.

Or what if you had a garden hose sprayer with fertilizer or insecticides hooked up when the incident occurred.
This is really only one example, and I'm sure there are many more, such as a sink sprayer left in dirty dish water.

The best protection against this is a simple backflow preventer that is attached to your outdoor hose bibs. (Available at your local hardware for about 5 bucks.) These are required at all food handling facilities.

Do you have them at your home?
Do you think you need them?
Will you be getting any soon?

MilitantSquatter 05-29-2006 07:07 PM

Thanks for the insight Joe... The garden hose fertilizer spray opened my eyes up.... It's probably the only time I'd have any concern regarding my outdoor connection. I'm surprised that this is not mandatory for residential everywhere.

I'll check into buying the backflow preventer next trip out. $5 won't hurt.

BBQchef33 05-29-2006 08:07 PM

Does this apply when your hooked up to municipal or city water with constant pressure? i cant se how a negative pressure can result and cause a syphon from my pool(or whatever). It would have to get thru the valves to the hose. Does this only apply to wells?

bbqjoe 05-29-2006 08:14 PM

I found this while searching your question:

Without proper protection devices, something as useful as your garden hose has the potential to poison your home's water supply. In fact, over half of the nations cross connections involve unprotected garden hoses.
What is a "cross-connection?" A cross-connection is a permanent or temporary piping arrangement which can allow your drinking water to be contaminated if a backflow condition occurs.
What is "backflow?" It's just what it sounds like: the water is flowing in the opposite direction from its normal flow. With the direction of flow reversed, due to a change in pressures, backflow can allow contaminants to enter our drinking water system through cross-connection.
A potentially hazardous cross-connection occurs every time someone uses a garden hose sprayer to apply insecticides or herbicides to their lawn. Another cross-connection occurs when someone uses their garden hose to clear a stoppage in their sewer line.
Without a backflow prevention device between your hose and hose bibb (spigot or outside faucet), the contents of the hose and anything it is connected to can backflow into the piping system and contaminate your drinking water.
This hazardous situation sometimes can affect more than a single home. In 1977, an entire town in North Dakota had to be rationed drinking water from National Guard water trucks while the town's water distribution system was flushed and disinfected following contamination by DDT. Investigation determined that two residents spraying DDT had made direct cross-connection to their homes. A backflow condition had occurred, sucking the DDT through the home piping systems andout into the town's water system.
Backflows due to cross-connections are serious plumbing problems. They can cause sickness and even death. However, they can be avoided by the use of proper protection devices. Each spigot at your home should have a hose-bibb vacuum breaker installed. This is a simple, inexpensive device which can be purchased at any plumbing or hardware store. Installation is as easy as attaching your garden hose to a spigot.

midnight 05-29-2006 09:43 PM

I used to work in the Plumbing field years ago and we had a news article cliped from a paper that we had hanging on our bulitin board.

It was a story about a school that had a red tint in the water coming out of their faucets and their drinking fountains. They had a local plumber come and check out their water lines and he couldn't find what the problem was. Luckily the school called the health dept to come test the water, they were worried it was rust or contained lead. The health dept. began investigating the problem.

What they found: A funeral home about a block away had an embalming table with a sink at the end for catching "fluids" from the dead bodies. They would rinse out the sink with a small length of garden hose attached to the sink faucet. The hose was never disconected and was long enough to touch the bottom and all the "fluids". When the school was in session all the water it used created a negative preassure and caused the fluids to be sucked up and back into the water supply where it was thinned out with all the fresh water leaving just a trace of pink in the water, and right on out the drinking fountains at the school!!

All it took to fix the problem was a backflow preventer and a shorter piece of garden hose.

bbqjoe 05-29-2006 11:10 PM

Thank you Midnight for that "Colorful" verification.

Arlin_MacRae 05-30-2006 08:59 AM


I've never even heard of a "backflow condition". Thanks for starting this thread, Joe!

CharlieBeasley 05-30-2006 11:24 AM

More great information but 5 dollars for everyone on the public water you are on could get expensive. With all the BS regulations we have to protect us from our selves one would think the city \ public water sources would have a means of preventing this for us all "Dead Body Fluids I knew I did not like to drink water. More Beer!

chad 05-30-2006 11:31 AM

There was a '70s or early '80s "made for TV" movie about a stadium that was having a lot of problems with people getting sick...lot's of polyester and blow dry hair-dos!! Turned out a utility sink with hose as the was backflowing wash water into the drinking system and one water cooler in particular...

Actually, from what I remember it was a pretty well done movie...

Sawdustguy 06-04-2006 01:15 AM

I don't know about you guys but when I installed my lawn sprinkler system I found out that code was to have double check and anti-siphon valves to protect against this very thing. I also found out there was no such code for our domestic water system so I installed double check and anti-siphon valves on my domestic water supply at the entrance to my house just after the meter.

ZILLA 06-04-2006 09:05 AM

So could my homes water system be contaminated by my neighbors water system if they have a problem with back flow?

bbqjoe 06-04-2006 10:50 AM


Originally Posted by ZILLA
So could my homes water system be contaminated by my neighbors water system if they have a problem with back flow?

If you are on a public water system, the answer is yes.

qman 06-04-2006 04:31 PM

City code in Orlando requires back-flow prevention on all outside bibbs, residential and commercial, and as Joe said, any hose bibb in a health regulated area.

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