Whenever there is a chance of dirty water being ‘sucked’ back into the water pipe we are forced to install a backflow preventor valve. Garden hoses are like this. Other water taps have to have a air gap, so even if the basin fills up and overflows, and a reversal of pressure happens at that time all that will be sucked back would be air.
FYI reversals of flows sometimes happen when the fire dept hooks up a intake hose to a hydrant, and the truck 'suck’s the water up at a very high rate through a pump.
So are these shower heads that one can move around because they are at the end of a hose illegal? If so why are they so available, if not why not? I doubt that showers have a back flow arrestor built into them, perhaps I’m wrong.
It always seemed like a bad idea to start with as you can spray water ‘up’ at one’s neither reagons and water doing what it does will come back down onto the showerhead - the same one you use to wash your hair- yuck! But if these things are left in a tub filled with water (perhaps because you had to get out due to a fire), and a backflow were to occur you would have your dirty bath water in everyone’s drinking water - triple yuck!!!
I don’t understand this objection – I d this all the time. There’s plenty of running water and the head gets rinsed off many times.
Consider: When you’re soaking in the bath every single part of you is sharing water that is lapping about your nethermost regions!!! Even your hair, if you’re lying that far down. Yuck!
But maybe you don’t take baths. For that reason.
Pressure in our house is 60 psi. A valve limits it, so the pressure out under the street must be at least a bit higher. A foot or two of water doesn’t have nearly that pressure, so I don’t see why it would flow back. Those hoses are maybe 4 feet long, so you could maybe get 2 or 3 psi if the water was all the way up to the spigot. It shouldn’t be a problem unless you’re installing them in a very odd place.
Older homes don’t have them, but many newer homes have a backflow preventer for the whole house. Any backflow will not be shared with your neighbors, at least.
I don’t understand this OP at all. With a garden hose, or anything attached to it, such as a shower head, or sprinkler, or anything else, if the faucet is open water will flow from the source (the pipes in the house) into the hose. When the faucet is closed, the water stops flowing.
There is no way that water will get from through a closed faucet back into the house. And when the water is flowing, there is no pressure going back in the direction of the pipes.
The only way that I can see “backflow” would be if you attached a pump or some other source of pressure to the end of the hose and actively pushed water back through the hose with more pressure than coming from the pipes.
So what is the problem you’re trying to solve here?
Think so? Many natural bodies of water are contaminated with E. Coli bacteria from waterfowl poop and farm animal runoff. Does a bear…yes, that, too. Unless you live in a hospital OR, you’ll have to accept some level of bacterial contamination. However, if you wash your tender parts and the rest of you with soap and water, you’ll be reasonably free of germs for a while.
It happens commonly when a few fire trucks attach to hydrants, and activally pump out water. One truck can reduce pressure down a line to 0 or even negative, a second truck downstream will pull negative pressure on a smaller water main.
Another time it coudl happen is if the water main breaks, you line is getting no water onto it on one side and your open faucet drains back towards the break.
Another time it could happen is if everyone and his brother takes a shower at the some time, faster then the water can get to the main. If your house is at the end of the line and up a hill the pressure in the line in your house could be higher then the pressure from the water company and it could backflow.
Don’t know what your basis of knowledge is regarding pumper operations. We instruct operators to stop increasing engine RPMs when the compound gauge reaches 20 psig. This is done to allow for gauge error, because you don’t want to run the pump in a vacuum condition. In extreme circumstances, cavitation can damage the pump impeller, which is why operators are taught to preserve that margin of safety.
Backflow still happens, even if fire engines are trained to mimimize it. There are other potential causes, as kanickbird mentioned. Many municipalities require backflow prevention devices for individual residences; mine happens to only require them for businesses. The legality depends on your jurisdiction, from the state down to the water purveyor’s level.
And yes, the shower head on a hose should have a vacuum breaker in it at a minimum. I’m sure that many don’t.
(Backflow prevention device tester and cross-connection control specialist licensed in California, FWIW.)
There’s probably an allowance for non-permanent fixtures. A garden hose isn’t permanent, but your sprinkler system is. Hence your garden hose doesn’t need a backflow prevention device (in these parts, anyway), but the sprinkler system does. The shower head, too, isn’t permantly fixed in still, nasty water. It’s permanent fixing naturally prevents backflow.
I’m just making a conjecture; there are parallels that do exist in the electrical world (Christmas lights, carnival power, stuff like that).
I’ve pulled a vacuum on a hydrant several times in my career - our chief has stated “let me know when you reach 20 psi residual, I’ll let you know if you can go lower.” I’ve had the gauge hovering at the 0 mark, and I’ve pulled a draft on a 4" supply line (draft is a poor term, the hose went flat, and the pump got really, really angry - thats what the red button in the middle of the throttle knob is for).
We’ve also had problems at large fires in the lower elevations of town. The town’s height varies from 2’ above sea level to 180’. There’s usally only about 25 to 30psi at the highest part of town (poor planning back in the 1960’s - whatta you mean we should put the water tower at the highest part of town? thats crazy talk!), that gives you at least 75 psi at the lower ends of town, in most cases you can get 120 psi static, and 80 psi or so residual at 750 gpm. When we pull several thousand gpm in that part of town, it drops the higher elevations into vacuum.
The town also had a pump failure on June 29, 1999 that emptied the town’s water tanks - the same ones that aren’t as high as the highest part of town. Gravity being how it is, the water in the pipes in the higher parts of town departed for the lower parts of town. In the meantime, water heaters were trying to jump through basement walls, and people were opening faucets to hear air go in, not water coming out. A good time had by all.
I was never a vacuum breaker/backflow preventer kind of guy, but after living here as long as I have, my mind is changed.
