Stubborn ancient bib tap

[JohnW2]

There are regs in place to prevent legionella in pipework (temps/dead legs etc). No such rules for hoses.

Are you suggesting that there should be such regs in relation to hoses (although I can't imagine what those regs would be).

If (in the manner suggested by RG) Legionella proliferate in a hose full of water, sitting in the sun for a long time, and then someone eventually 'squeezes the trigger' and sprays that Legionella-laden water all over his/her family, that would definitely represent a health risk, but no number of check valves would prevent that.

Kind Regards, John

 

[denso13]

That sounds logical, but I'm not sure how one would set about trying to 'stop Legionella forming' in cold water pipework through which there was no flow.

There's more to this plumbing caper than people realise.

We have seen this a lot in relation to electrical matters, currently probably most apparent in relation to SPDs and AFDs, which are gradually moving in the direction of becoming 'more required'!

Noted. One difference is that backflow prevention isn't new. The regs were written in 1999 and I was taught about it in the seventies and have fitted countless check valves over the years. Perhaps a bit late to the party on this one...

Are you suggesting that there should be such regs in relation to hoses (although I can't imagine what those regs would be).

No, that would be unreasonable.

 

[denso13]

although I would point out that I was told early in this thread that check valves incorporated into 'hose taps' were not generally 'acceptable'

They are not allowed by the regs in a new tap installation. They are allowed if changing an existing tap.

 

[RandomGrinch]

any event, what RandomGrinch has said suggests that air breaks may not be a panacea. If 'stagnant' water in a hose can breed bacteria, to subsequently be 'sucked' into the installation's pipework, then the same can presumably happen in run of pipe to an upper floor in which there has not been any flow for a long time.

I'm afraid I don't know the true level of risk - presumably small (although multiplied by many, many taps! ) - but it does form part of our institutions legionella control measures.
If dead legs are identified, they are removed.
Our taps are separated into three categories:
Frequently used: are inspected and flushed as part of the formal legionella inspection and tank treatment programme.
Infrequently used: are additionally run through and flushed weekly.
Unused (but with the potential for re-use): are isolated at the branch, drained and left open.

If (in the manner suggested by RG) Legionella proliferate in a hose full of water, sitting in the sun for a long time, and then someone eventually 'squeezes the trigger' and sprays that Legionella-laden water all over his/her family, that would definitely represent a health risk, but no number of check valves would prevent that.

Which is where media campaigns may help - just an example of the latest one I could find:

Warning over 'deadly' health condition thriving in garden equipment and pools

People are more at risk of catching Legionnaires' disease in the summer thanks to the warmer temperatures.

www.dailyrecord.co.uk

 

[JohnW2]

Noted. One difference is that backflow prevention isn't new. The regs were written in 1999 and I was taught about it in the seventies and have fitted countless check valves over the years. Perhaps a bit late to the party on this one...

Matters electrical are not really that different. RCDs have existed since the 1970s (and undoubtedly were being 'taught about' back then), but it was only in 2018 that RCD protection of virtually all final circuits became 'required' by regulations.

Kind Regards, John

 

[JohnW2]

They are not allowed by the regs in a new tap installation. They are allowed if changing an existing tap.

Again, that is a (fairly common) anomaly of regs which is seen with both water and electrical ones. A particular practice is either considered to be acceptable/'safe' or not - and does not (should not) depend upon whether it is a new installation or a 'perpetuation' of something that was previously there!

Kind Regards, John

 

[JohnW2]

I'm afraid I don't know the true level of risk - presumably small (although multiplied by many, many taps! )

You're obviously not alone. At least one reason why neither denso nor myself know "how often backflow incidents happen" is that there is really no way that such statistics could really exist, since the vast majority of 'backflow incidents' presumably go unknown and undetected?

- but it does form part of our institutions legionella control measures.
If dead legs are identified, they are removed.
Our taps are separated into three categories:
Frequently used: are inspected and flushed as part of the formal legionella inspection and tank treatment programme.
Infrequently used: are additionally run through and flushed weekly.
Unused (but with the potential for re-use): are isolated at the branch, drained and left open.

Interesting - but clearly not something that happens in domestic installations (even if 'it should'!). However, we have now slid a fair way laterally from the topic of backflow and backflow prevention

Kind Regards, John

 

[JohnW2]

Interesting - but clearly not something that happens in domestic installations (even if 'it should'!).

@RandomGrinch - you previously wrote:

Infrequently used: are additionally run through and flushed weekly.
Unused (but with the potential for re-use): are isolated at the branch, drained and left open.

Since we live in a house which is now far too big for (usually) just the two of us, there are dusty corners, some with water supplies, which are very rarely used (other than at Christmas etc.), so there are probably some taps/pipes which can go literally for months without any flow.

However, I can offer a far more dramatic anecdote than that. I first saw the house referred to in my OP in recent times (I'd seen it decades earlier) about six months ago. Before I turned the water supply to the house on, I turned on the kitchen tap, and a significant amount of water came out, gradually slowing and stopping completely after about 30 seconds or so (hence seemingly indicating that the stopcock was largely doing its job). Unless there had been a very small leakage past the stopcock, that water must have been coming from the pipes which went upstairs -just two, separate, (lead) pipes, one going to a toilet and the other to a hand basin. If that was the case, the amazing thing is that house had been unoccupied, with water 'turned off' for over 20 years!

Kind Regards, John

 

[Harry Bloomfield]

Since we live in a house which is now far too big for (usually) just the two of us, there are dusty corners, some with water supplies, which are very rarely used (other than at Christmas etc.), so there are probably some taps/pipes which can go literally for months without any flow.

I used to look after a certain high street/and select banking chain. Some of their building were far, far bigger than their needs, with several massive floors unused. One of the regular things to keep an eye on, was dead-legs and making sure less used taps got some use.

I have this morning fitted a third garden tap at home, I made absolutely sure, that like the rest, it had a double check valve. The risk of contaminated water flowing back into the mains might be small, but the potential for damaging other people's health is very real.

 

[JohnW2]

I used to look after a certain high street/and select banking chain. Some of their building were far, far bigger than their needs, with several massive floors unused. One of the regular things to keep an eye on, was dead-legs and making sure less used taps got some use.

Yes, that all makes sense. As I said, I have a similar situation in my home butI have to admit that it's never really occurred to me to 'make sure that less used taps get some use'.

I have this morning fitted a third garden tap at home, I made absolutely sure, that like the rest, it had a double check valve. The risk of contaminated water flowing back into the mains might be small, but the pial for damaging other people's health is very real.

It can't do any harm. However, whether it's to do with water, electricity or anything else, there is always the question of how probable an 'extremely improbable' risk needs to be to justify taking steps to address it - if we didn't engage in such thinking, even if subconsciously, we'd find ourselves doing countless things (quite possibly at a significant, financial, environmental or whatever cost) to address theoretical risks that were incredibly small. As we often see in the Electrics forum, a few people are far more 'risk-averse' than others, even though the world, and daily life, is full of 'risks'.

For what it's worth, and albeit without any 'proof', it remains my intuitive view that backflow into the supply network from a hose being used at roughly ground level is probably an extremely rare event and, furthermore, that even if/when it does happens, the probability of it resulting in any harm (to health) is also probably pretty (quite probably 'very') small.

A check valve will certainly reduce that risk (however small) even further but this very thread illustrates that one has to ask 'how far to go'. We have been reminded in this thread that 'check valves can fail' - so, if one believes that check valves are essential in this situation, then one would logically say that there should be at least two? (just as the same argument could be used to require duplication of MCBs, RCDs and RCBOs - all of which can fail to operate correctly when required so to do).

Kind Regards, John

 

[Harry Bloomfield]

A check valve will certainly reduce that risk (however small) even further but this very thread illustrates that one has to ask 'how far to go'. We have been reminded in this thread that 'check valves can fail' - so, if one believes that check valves are essential in this situation, then one would logically say that there should be at least two? (just as the same argument could be used to require duplication of MCBs, RCDs and RCBOs - all of which can fail to operate correctly when required so to do).

Well, I know there are check valves, and double check valves, but I've never explored the difference, or the 'mechanical arrangement'.

 

[JohnW2]

Well, I know there are check valves, and double check valves, but I've never explored the difference, or the 'mechanical arrangement'.

As I understand it, a double check valve is simply two in series, with two 'advantages' - firstly redundancy - i.e. if one fails, then the other is there as a backup. Secondly, when the first one 'operates' as a result of an attempted backflow, it reduces the pressure on the second one, thereby maybe enabling it to seal more effectively/certainly.

However, I had assumed that when CBW reminded us that check valves 'can and do fail', he was probably talking about double ones - so, in terms of my question about 'how far should we go?', the question is whether, if one regards check valve functionality as crucial, the requirement should perhaps be for two double check valves in series

Kind Regards, John

 

[Elkato531]

Did you manage to change your tap?

 

[JohnW2]

Did you manage to change your tap?

As I said, it will be a week or two before I am next there (it's a bit over 100 miles from where I live), and I'll report back after that.

In the meantime, an 'in passing' comment from me about backflow and check valves seems to have resulted in a few pages of 'tangential discussion'

Kind Regards, John

 

[JohnW2]

One 'spanner' on the tap, something else helping to take the torque on the pipe, so the arms of both are at a similar angle, close to each other - then fit a lever between them, to apply the brute force.

It's still a while before I'm going to be reunited with the tap again (my greatest hopes still being in 'heat') but, in the meantime, I've found a photo which gives a little insight into the 'access' problem (restriction on getting decent length pipes onto a spanner, as below.

As I said at the strat, the whole place obvioulsy needs a new plumbing installation 'from scratch', and I'm starting to think conceptually about ways in which that could be arranged and engineered. I'll therefore probably be asking a number of further questions about those 'concepts'(and some details!).

Kind Regards, John