Replies

1. 
   Stuart | Jan 07, 2006 06:39am | #1

   It's a little device that threads on your faucet to prevent any water from backflowing back into the pipe, so you don't get any contamination.  This looks like a pretty good explanation: http://www.irrigationtutorials.com/sprinkler08.htm

   Surprisingly, it turns out there's an American Backflow Prevention Association.  http://abpa.org/

    

1. 
   Hoohuli | Jan 07, 2006 06:56am | #3

   Surprisingly???
   Over here a separate license is required to install BVD's. You'll notice that almost all commercial/industrial areas have them somewhere on the property to separate out their water from the municipality general water supply. BVD's are everywhere, expecially in low pressure areas and alot of codes require them. It can be a very complicated subject, for example some areas will not allow double check system, but require only AVB's. An Assoc. is the only way to keep up to date on regs and products.

1. 
   Stuart | Jan 07, 2006 07:03am | #4

   Perhaps I should have said interestingly instead of surprisingly... :-)  I've seen plenty of backflow preventers on construction projects (I'm an EE who works on municipal water projects.)  I understand why they are used but as a non-plumbing person I didn't know there was that much to them.

   Edited 1/6/2006 11:05 pm ET by Stuart

1. 
   akjim | Jan 07, 2006 07:42am | #5

   Thanks for the good info. Kind of what I thought. My situation: rural home with its own well and septic system. This install is a tub faucet for a second story bath. Unnecessary in this application. Onward!
   Jim

1. 
   BillHartmann | Jan 07, 2006 08:32am | #7

   " My situation: rural home with its own well and septic system. This install is a tub faucet for a second story bath.Unnecessary in this application."IF NEEDED! then it would still be appropriate as you could contaminate the drinking water in the house.However, it is not needed in this case.In most cases there will be an air gap between the spout and the the flood rim of the tub. That will prevent the waste water from ever getting into the supply lines.Now hand shower attacments like these do need one and the end can end up in the tub water.http://www.vintagetub.com/asp/feature_item.asp?cat=78&subcat=35And the sell a vacum breaker just for that reason.

   Edited 1/7/2006 12:35 am by BillHartmann

2. 
   JRuss | Jan 07, 2006 05:50pm | #8

   I agree with Bill H, just because you are rural, on a well, or are residential doesn't alter the siphoning principle.  Most fixtures today for these applications, all are supposed to, have vacuum brakes.  However, a flexible shower wand dropped into a sink or tub can be a problem, especially on an upper floor.  You will probably have safe fixtures and installation, but the attention and prevention of siphoning can't be stressed enough.  It's one area to over kill.Never serious, but always right.

2. 
   Hoohuli | Jan 07, 2006 07:48am | #6

   Sorry, maybe I jumped a little hard, but this is one area I feel strongly about. I do irrigation design, and repairs and try to keep up on the laws. Always keeping in mind that h20 will be the oil of the future, sounds like the WaterBoy, oh well. Living on an island our water is very limited and so many system are installed with no BP of any kind. Also, no inspections of irrigation system installations is required and no backflow is required as a stub out during initial construction. The laws are screwed up, but the idea is right, protect the water.

2. 
   Hoohuli | Jan 07, 2006 06:47am | #2

   Backflow Preventer are just what their name implies, they stop water from going backwards. The idea is that at times syphoning can occur from a contaminated source and flow backwards into the main water system, thus contaminating your drinking water. Normally you find them separating out the irrigation system from your house supply and on each exterior hose bib. If the pressure to your house is lost for some reason a hose lying in a puddle cannot back syphon from the puddle or pool back into the water supply and contaminate your house and all the other homes on the line. They can be expensive double check preventers, atmospheric vacuum breakers, or simple flap valves inline. I'm not quite sure what you mean by a Roman fawcet, but as long as the spout is above the water line I see no need for a backflow device.