What are the possible issues with outdoor faucets contaminating indoor water supply?

[rx2waveplumb]

I'm new to plumbing as new homeowner and so have I been performing some simple plumbing and found that it's kind of fun. I love to learn and I was reading up on outdoor faucets and the design of frost free anti-siphon outdoor faucets and the reasons for the anti-siphon mechanism which is to prevent backwards flow of some sort of contamination into the main supply with providing a pressure mechanism. This is where I became confused and realized this part is probably the most serious and so I'm asking for maybe a generalized explanation to all the possible issues with outdoor faucets (even non-frost free) that plumbers have to mitigate for all outdoor lines coming into the main supply of the home?

I had to repair mine and honestly if I didn't read up on that, I would have left it exposed without the cap on my frost freeze faucet. Maybe I'm overestimating the risks but bacteria and other contaminants leaking into my main supply are serious concerns.


Thanks

 

[Reach4]

I'm asking for maybe a generalized explanation to all the possible issues with outdoor faucets

You ask for too much.

 

[Sponsor]

 

[Terry]

Codes now require antisiphon connections at the hoses now. During a shutdown, hoses were able to drain back into the homes and into the adjoining public water systems. This was most noticeable from restaurants, and add to that people using outside hosebibs for irrigation. Imagine how many feet of pipe laying underground that could be siphoning back into the water supplies.
Irrigation systems are typically installed with either a vacuum breaker at the high point, or if lower, a reduced pressure back flow device.
I haven't installed a non anti-siphon in decades. Keeping our water systems pure is very important.

 

[LLigetfa]

There is more to it than just an anti-siphon vacuum breaker. There is a need to prevent back-flow. A hose or tubing connected to an outside hose bib can act as a pressure reservoir and if/when there is a pressure drop, some of the water in the hose can flow back into the potable water supply.

 

[Jadnashua]

While irrigation systems generally require back flow preventers (some places require them to be tested annually), all outdoor hose bibs should be anti-siphon in addition. FWIW, most toilet fill valves have that requirement as do hand-held shower wands, and sprayers on sinks. That's one reason why the code was modified ages ago so that the bathtub fill valve had to be above the rim of the tub (many really old ones, the spout was in the tub and could end up sitting in the water if you filled the tub too high).

In normal circumstances, it wouldn't be an issue, but if there's a hiccup in the system, that hose could be sitting in the cow manure you just added for fertilizer, and get sucked back into the water supply along with the insecticide you added for good measure! Those don't happen all that often, but they can and do. One thing that can affect the pressure is fire fighting when they open up lots of fire hydrants, but there are other causes as well.

 

[FullySprinklered]

This is an extreme case, but here goes:

Fellow I knew still lives on the family farm. Makes a living running a bank of computers in a trailer on his property, having created a program to fill a need in a certain business with a massive cash flow.

The place still functions as a working farm, though on a small scale. Still runs a small herd of cows on the property. The cows roam freely around the house and pastures thanks to a cattle gap down by the road. Dirt road.

On the side of his house he has a spigot with a short hose dropped down into a large trough to water the cows. The trough has green algae, mosquito larvae, tadpoles and God knows what else living in there. He's on a well.

Now, if he leaves the spigot on, and there's a power outage, there's a chance that all that disgusting swill in the watering trough could get sucked back into the water pipes in the house and maybe even down the well, depending on the check valve situation.

So there you go. It could happen.

 

[Terry]

When I travel, I see lots of examples of what not to do. And they always warn you about drinking the water.
There should always be an air gap between the spigot and the overflow of the basin. That is why the tub faucet is always higher than the tub. That way the water can't jump up into the pure water supply. The more people on a water system, the more chances for a cross connection and people getting sick.

These guys aren't very happy about having to buy bottled water instead of drinking out of the tap.

 

[FullySprinklered]

My drinking/cooking/washing water is heavily filtered. Bored well is in a ravine in front of the house. Upstream past the driveway is the neighbor's property that looks suspiciously like an equine-friendly environment. I buy water and ice at the grocery store.

 

[rx2waveplumb]

Codes now require antisiphon connections at the hoses now. During a shutdown, hoses were able to drain back into the homes and into the adjoining public water systems. This was most noticeable from restaurants, and add to that people using outside hosebibs for irrigation. Imagine how many feet of pipe laying underground that could be siphoning back into the water supplies.
Irrigation systems are typically installed with either a vacuum breaker at the high point, or if lower, a reduced pressure back flow device.
I haven't installed a non anti-siphon in decades. Keeping our water systems pure is very important.

There is more to it than just an anti-siphon vacuum breaker. There is a need to prevent back-flow. A hose or tubing connected to an outside hose bib can act as a pressure reservoir and if/when there is a pressure drop, some of the water in the hose can flow back into the potable water supply.

While irrigation systems generally require back flow preventers (some places require them to be tested annually), all outdoor hose bibs should be anti-siphon in addition. FWIW, most toilet fill valves have that requirement as do hand-held shower wands, and sprayers on sinks. That's one reason why the code was modified ages ago so that the bathtub fill valve had to be above the rim of the tub (many really old ones, the spout was in the tub and could end up sitting in the water if you filled the tub too high).

In normal circumstances, it wouldn't be an issue, but if there's a hiccup in the system, that hose could be sitting in the cow manure you just added for fertilizer, and get sucked back into the water supply along with the insecticide you added for good measure! Those don't happen all that often, but they can and do. One thing that can affect the pressure is fire fighting when they open up lots of fire hydrants, but there are other causes as well.

Thanks for replying, despite the broadness of my question, you guys were still managed to able to explain and paint a picture for me to get a gist of the importance of anti-siphoning different points through the system. For example I wouldn't have ever considered or at least realized the point past the home where there cond be a risk to the public system supplying the whole neighborhood. I would imagine due to the the possibility of error or overlook in public enforcement of code and/or possibility of a home DIY plumber some how screwing up and contaminating the water supply, that the city's public water maintains the prevent of siphoning at their supply point to the house "just in case". The pictures below provided by Terry was a great reason for an air gap, when I was traveled same region, I noticed that as well but didn't consider it now. Thanks

This is an extreme case, but here goes:

Fellow I knew still lives on the family farm. Makes a living running a bank of computers in a trailer on his property, having created a program to fill a need in a certain business with a massive cash flow.

The place still functions as a working farm, though on a small scale. Still runs a small herd of cows on the property. The cows roam freely around the house and pastures thanks to a cattle gap down by the road. Dirt road.

On the side of his house he has a spigot with a short hose dropped down into a large trough to water the cows. The trough has green algae, mosquito larvae, tadpoles and God knows what else living in there. He's on a well.

Now, if he leaves the spigot on, and there's a power outage, there's a chance that all that disgusting swill in the watering trough could get sucked back into the water pipes in the house and maybe even down the well, depending on the check valve situation.

So there you go. It could happen.

Just out of curiosity does he still run his server farm? With Amazon's AWS or other cloud services he probably doesn't do that much now and probably capitalized on it in the late 1990's to early 2000's.

 

[FullySprinklered]

Thanks for replying, despite the broadness of my question, you guys were still managed to able to explain and paint a picture for me to get a gist of the importance of anti-siphoning different points through the system. For example I wouldn't have ever considered or at least realized the point past the home where there cond be a risk to the public system supplying the whole neighborhood. I would imagine due to the the possibility of error or overlook in public enforcement of code and/or possibility of a home DIY plumber some how screwing up and contaminating the water supply, that the city's public water maintains the prevent of siphoning at their supply point to the house "just in case". The pictures below provided by Terry was a great reason for an air gap, when I was traveled same region, I noticed that as well but didn't consider it now. Thanks



Just out of curiosity does he still run his server farm? With Amazon's AWS or other cloud services he probably doesn't do that much now and probably capitalized on it in the late 1990's to early 2000's.

Not sure, it's been 15 years since I've seen him. Looked like he might have been on his way to Betty Ford.