Garden taps are one way valves. Doh!!

[alchemysa]

Desiring to flush my empty rainwater tank with some bore water I thought an easy solution would simply be to connect a garden hose from the bore tap to a a tap on the rainwater tank, and then open both taps.

No go!... Pump problem? No. Kink in the hose? No. It took me a while to realise that a common garden tap like the one pictured is a one way valve. You can't pump water backwards into a garden tap. Its amazing how we sometimes don't know the simplest things.

 

[tallyho8]

Although these are required by the building code to prevent feedback into the system when the water pressure gets low, I have never seen one yet in our local box stores.

They are probably more common in some areas.

 

[alchemysa]

Although these are required by the building code to prevent feedback into the system when the water pressure gets low, I have never seen one yet in our local box stores.

They are probably more common in some areas.

I think you might misunderstand my point. I'm saying that ANY tap with an ordinary round rubber washer style of seal like the one illustrated below is naturally a one way valve. So the same would apply to a common kitchen or bathroom tap.

The thing to remember is that the valve seal is opened by the pressure from the main source. Its NOT 'pulled' open' by the tap.

 

[arsenix2001]

Uh I dont think so... We have indoor riser pipes with spigot valves at the top and an on off valve at the floor with a freeze drain. If i open my spigots and have the water shut off, water flows backward from the hose through the spigot no problem. I suspect you have a "to code" valve that acts as a check valve and back drains to prevent freezing. We have run of the mill home depot off the shelf spigots with rubber gaskets and they flow both ways just fine! :thumbsup:

 

[alchemysa]

Uh I dont think so... We have indoor riser pipes with spigot valves at the top and an on off valve at the floor with a freeze drain. If i open my spigots and have the water shut off, water flows backward from the hose through the spigot no problem. I suspect you have a "to code" valve that acts as a check valve and back drains to prevent freezing. We have run of the mill home depot off the shelf spigots with rubber gaskets and they flow both ways just fine! :thumbsup:

By 'spigot' I guess you mean an ordinary tap with a rubber valve rather than an all metal valve like a gate valve? (Oops yes you said that.)

Anyway, I would suggest it depends on the the amount of water pressure applied 'in reverse.' Simply draining the water as you describe may not provide enough pressure to seal the valve, but try actually pumping backwards into the tap and you might discover its a different outcome.

 

[tallyho8]

Our faucets are simple open and shut regardless of pressure. See Photo. Water can flow either way at any pressure. They do not have a backflow prevention device like your faucet.

Our valve seal IS pulled open by the tap and NOT opened by the pressure from the source.

 

[alchemysa]

Our faucets are simple open and shut regardless of pressure. See Photo. Water can flow either way at any pressure. They do not have a backflow prevention device like your faucet.

Our valve seal IS pulled open by the tap and NOT opened by the pressure from the source.

That diagram does not necessarily indicate that the seal is opened by the tap. It simply shows a tap with a 'stem washer' that has possibly been opened by water pressure.

Anyway, I'll take your word for it that your taps have the washer fixed to the spindle. But I must admit that surprises me. I've changed plenty of washers in garden and indoor taps and I've only ever come across the 'stem' type illustrated in my previous post.

 

[irvingj]

Yep- it's the "jumper" located in the Australian faucet-- looks like it's not attached to the stem and is free to drop back down if it encounters pressure from the hose side; the stem just clamps it down for valve closure on the source side.

Ours are definitely screwed to the end of the stem, often with a very rusty screw that refuses to come out when you try to change the washer!

 

[tallyho8]

It appears that the building codes are much stricter in the Land of Oz than they are here. We are required to have a "vacuum break" that screws on the end of outdoor faucets but they are never inspected after the initial inspection and are usually thrown away shortly after installation.

There was a famous case a while back where a pest control company was filling a bucket containing chlordane with a water hose and the water company turned off the water in the neighborhood for repairs.

The chlordane got sucked back up into the water system and spread throughout the system. Both parties had to pay very expensive penalties to replace the water system in the area.

 

[SandburRanch]

The only garden taps I'll have are this style. I wanted to put two ( hot and cold ) at the kitchen sink in the new house we built 25 years ago but the wife wouldn't go for it. Narrow minded woman.

http://www.northerntool.com/downloads/manuals/18572.pdf