handheld bidet - backflow preventer

Forums › Home Workshop DIY › handheld bidet - backflow preventer

greenbone

176 posts

Master Geek

#147247 13-Jun-2014 12:16

so if youve been to south east asia, youre probably familiar with a toilet hose, or handheld bidet

washing vs smearing seems pretty straight forward to me so im keen on installing one

so from what ive read, a check valve / one way valve / non return valve will comply in Aus and Asia, but in NZ an AVB (atmospheric vacuum breaker) which provides at least a 25mm air gap is required ...

does anyone know much about this? im comfortable with a (lot cheaper) check valve as long as its going to prevent backflow contamination

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Vocus

#1064832 13-Jun-2014 12:26

As I understand it, you can't DIY work like this legally in NZ, it has to be done by a licensed plumber. Technically you may need building consent too, although I'm not certain.

Tradepub

Free professional, reference and technical white papers (affiliate link).

Aredwood

3885 posts

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#1064842 13-Jun-2014 12:46

If you want to fully comply with the NZ Backflow rules. The only devices allowed for backflow prevention on one of those toilet sprayers. (Which are classed as a high hazard - same as chemical plants ect). Is either a reduced pressure zone. Or pressure vacuum breaker valve. Atmospheric vacuum breakers are only permitted for situations where there isn't any tap or valve on the outlet side of the Atmospheric vacuum breaker. A single check valve isn't even approved for low hazard rated applications.

Unfortunatly both reduced pressure zone and pressure vacuum breaker valves are bloody expensive. Retail is easily $500 just for the valve, If you find a new one for less than about $250 snap it up. Also pressure vacuum breakers must be installed higher than the fixture / outlet protected. Got to go to a job now but happy to answer any more questions.

Coil

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#1064851 13-Jun-2014 12:57

Why you need the valve?
As long as the lines pressured no water is going back down the hose??

ubergeeknz

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#1064853 13-Jun-2014 13:01

TimA:
Why you need the valve?
As long as the lines pressured no water is going back down the hose??

And if it falls in the bowl and pressure is lost for some reason? Or due to some problem there is negative pressure on that outlet? Then you have a contaminated water supply. This is why plumbing work has to be done by plumbers...

Coil

6614 posts

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#1064862 13-Jun-2014 13:10

ubergeeknz:
TimA:
Why you need the valve?
As long as the lines pressured no water is going back down the hose??

And if it falls in the bowl and pressure is lost for some reason? Or due to some problem there is negative pressure on that outlet? Then you have a contaminated water supply. This is why plumbing work has to be done by plumbers...

Hold on. The toilet bowl is fed by the res that has a valve on it etc, That has a 1 way valve. So none of the res water can get back into the water supply.
What it looks like he wants to do is put on a hose thing that will go off the wall tap. Thats no where near the toilet res or bowl.. Why does a separate "hose" need to be 1 way?
So what he wants is 1 way on that hose?

andrewNZ

2487 posts

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#1064863 13-Jun-2014 13:10

There was a case quite a few years back where (I think) a dairy factory managed to back feed the town supply with cleaning solution. Burned quite a few people from memory.

MikeB4

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#1064865 13-Jun-2014 13:12

This will do it and cure hemorrhoids as well
And you can take it with you anywhere

solaybro

627 posts

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#1064867 13-Jun-2014 13:13

KiwiNZ: This will do it and cure hemorrhoids as well
And you can take it with you anywhere

Every use comes with a free enema.

greenbone

176 posts

Master Geek

#1064868 13-Jun-2014 13:13

thanks for replies

Aredwood, lets say for a second, purely theoretically, that compliance and legalities dont exist ...

would you personally trust a check valve fitted between the cistern tap and bitdet attachment to prevent backwater contamination in 99% of cases?

greenbone

176 posts

Master Geek

#1064870 13-Jun-2014 13:17

Hold on. The toilet bowl is fed by the res that has a valve on it etc, That has a 1 way valve. So none of the res water can get back into the water supply.
What it looks like he wants to do is put on a hose thing that will go off the wall tap. Thats no where near the toilet res or bowl.. Why does a separate "hose" need to be 1 way?
So what he wants is 1 way on that hose?

i suppose its because the wash head attached to the end of the hose has a chance of getting poo on it

Coil

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#1064872 13-Jun-2014 13:19

greenbone:

Hold on. The toilet bowl is fed by the res that has a valve on it etc, That has a 1 way valve. So none of the res water can get back into the water supply.
What it looks like he wants to do is put on a hose thing that will go off the wall tap. Thats no where near the toilet res or bowl.. Why does a separate "hose" need to be 1 way?
So what he wants is 1 way on that hose?

i suppose its because the wash head attached to the end of the hose has a chance of getting poo on it

Fair.

You can get little fittings with a rubber seal with a ball bearing in them.

greenbone

176 posts

Master Geek

#1064876 13-Jun-2014 13:25

You can get little fittings with a rubber seal with a ball bearing in them.

yeah thats a check valve or one way valve. to me that seems like it would suffice. i mean the risk of backflow contamination in this setup would be tiny - you would have to have poo on the wash head and a significant loss of pressure for it to be sucked back into the supply. it would have to be a catastrophic loss of pressure for it to be sucked into the mains supply

greenbone

176 posts

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#1064889 13-Jun-2014 13:31

relevant:

greenbone

176 posts

Master Geek

#1064895 13-Jun-2014 13:45

got a callback from Reece plumbing; their advice is a dual check valve with 25mm air break, p# 104553, rrp $48.50+gst. think i will proceed

timmmay

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#1064934 13-Jun-2014 14:26

greenbone:

You can get little fittings with a rubber seal with a ball bearing in them.

yeah thats a check valve or one way valve. to me that seems like it would suffice. i mean the risk of backflow contamination in this setup would be tiny - you would have to have poo on the wash head and a significant loss of pressure for it to be sucked back into the supply. it would have to be a catastrophic loss of pressure for it to be sucked into the mains supply

Either that or a very high pressure human discharge.

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