Plumbing - A Cautionary Tale

[Flyfisher]

I had a visit yesterday from a very nice 'Industrial Water Regulations Technican' chap from Anglian Water who asked me if I'd been having any problems with our water supply (we haven't).

Apparently, he'd been called in to investigate blue water coming out of some neighbour's mains taps. It turns out that the toilet cisterns in these houses are fitted with those modern 'push-button' devices and, he explained, their installation and correct set-up is quite critical to ensure a correct air gap and thus prevent back-siphonage. Anyway, it seems that whoever installed these units had done it incorrectly and cistern water was able to travel back into the mains supply.

He reckoned that this must have been happening for years but it only came to light when one of the occupiers recently used one of those "blue loo" things, hence the blue water in the mains taps. Yeuk!

I'd never heard of this problem before but he said it was quite common with this type of valve because they are so often installed incorrectly and he spends a lot of his time resolving such problems. So, if anyone does install these things, pay very careful attention to the instructions.

 

[jocelyn plummer]

Just goes to show what new fangled -- must have as directed by our nanny state --technology can do.!!

 

[robgil]

Just goes to show what new fangled -- must have as directed by our nanny state --technology can do.!!

Some plumbing materials , although legal to buy , are illegal to fit.

Kitchen sinks with the shower head on a tube for rinsing for instance.

These ones.

Sorry , it's the first photo I could find in google images with the head and pipe extended to full length.

 

[LadyArowana]

Just goes to show what new fangled -- must have as directed by our nanny state --technology can do.!!

Some plumbing materials , although legal to buy , are illegal to fit.

Kitchen sinks with the shower head on a tube for rinsing for instance.

These ones.

Sorry , it's the first photo I could find in google images with the head and pipe extended to full length.

Oh, I don't think there is any need at all to apologise. Why are those fittings non approved though?

 

[MdB]

Oh, I don't think there is any need at all to apologise. Why are those fittings non approved though?

Back syphonage. If there is a back pressure in the water supply, your drinking water can be mixed with your washing up water.

 

[AMc]

Apparently, he'd been called in to investigate blue water coming out of some neighbour's mains taps.

Sounds disgusting, but at least it's only water from the cistern which is just a water tank albeit quite close to the bowl...until it's mixed with toilet cleaner! :shock:

 

[Moo]

Much cheaper (and legal, and efficient) are the spray adaptors sold by Lakeland: http://www.lakeland.co.uk/search/kitchen-sink-spray-attachment/q04.r16.1

 

[AMc]

Oh, I don't think there is any need at all to apologise. Why are those fittings non approved though?

Back syphonage. If there is a back pressure in the water supply, your drinking water can be mixed with your washing up water.

I've got something similar bought from a UK kitchen supplier - the end of the tap pulls out of the mixer on a flexible hose- had no idea there was any danger - you live and learn!

We stopped bathing our kid in the kitchen sink when she was a few months old - modern parents just won't let their kids grow up!

 

[Moo]

The kitchen sink is absolutely the best bath for small people.

 

[LadyArowana]

The kitchen sink is absolutely the best bath for small people.

Doesn't seem like a bad option for full grown chaps either :lol:

 

[Flyfisher]

Apparently, he'd been called in to investigate blue water coming out of some neighbour's mains taps.

Sounds disgusting, but at least it's only water from the cistern which is just a water tank albeit quite close to the bowl...until it's mixed with toilet cleaner! :shock:

Yes, as the Anglian Water chap said, the problem had probably existed for years before someone added 'blue loo' but at least the cistern water itself would be clean and regularly replenished, so perhaps not a big.

However, he did mentioned that these types of valves are also widely used in rainwater harvesting systems in new builds, where rainwater is collected and separately distributed to flush toilets. All well and good, but the storage tanks are also connected to the mains supply to keep them topped up in times of low rainfall and back-siphonage can put the occupants at risk. He mentioned a legionella risk due to attic tanks warming up during the summer months.

Having said that, I've never been particularly cautious about drinking water from bathroom taps (though I don't make a regular habit of it) and all our previous houses have had tanks in the attic - perhaps such carelessness has kept my immune system on its toes?

I wonder how long the disinfectant effect of water chlorination (or whatever they use these days) lasts in a tank of standing water?

 

[LadyArowana]

Most of us would be fine even if we did drink what was in the cistern ( without the loo cleaner of course )

 

[AMc]

However, he did mentioned that these types of valves are also widely used in rainwater harvesting systems in new builds, where rainwater is collected and separately distributed to flush toilets. All well and good, but the storage tanks are also connected to the mains supply to keep them topped up in times of low rainfall and back-siphonage can put the occupants at risk. He mentioned a legionella risk due to attic tanks warming up during the summer months.

I thought most rainwater harvesting tanks were buried which would keep them pretty cool year round?
If they were subject to legionella friendly heating in the summer they'd surely be subject to freezing in the winter.
Sounds like he's just trying to drum up more trade for mains water

As with almost all building work, the devil is in the details - but who checks or even knows to check?

 

[Onetap]

What the Inspector didn't mention is that back siphonage is usually prevented by the mains water pressure and only becomes a hazard in the event of mains failure due to an unusually high demand or a break. This does happen though, and you may then get the contents of a pond on high ground being siphoned out through a hose or worse; much, much worse. There are pages of requirements in the Water Regulations which specify the type of back-syphonage prevention device required for various fluid categories.

One of the commonest transgressions is a mains-fed shower hose fitted over a bath; the hose should pass through the ring on the rail to prevent it being immersed in the bath, but usually doesn't.

The traditional UK arrangement (one mains kitchen tap, everything else supplied from a cistern with an air gap at the inlet) was fairly fool-proof, but the regualtions were amended to allow the European mains fed systems. There are many cautionary horror stories about back-siphonage that have been accumulated in countries that have traditionally used mains-fed systems.

 

[Flyfisher]

I did ask how things could siphon back against the mains pressure and he said that it can happen in certain circumstances, but he then lost me when talking about hydraulic effects within the pipework. He seemed to know what he was talking about though and said he'd be quite happy to visit me again to advise on any future plumbing works we need to do. I've got his card if any EA PPUKers would like to contact him. He's based in Norwich. Not really appropriate to post it here, but PM me if anyone is interested.

AMC's point about rainwater harvesting tanks being buried could well be right. I may have been confusing that with his other recollection (he was a fast and enthusiastic talker) of a similar problem in a care home where the attic tank was similarly affected and when he investigated it turned out to be an open tank with about six inches of sludge in the bottom.

The point about the devil being in the detail is so true though . . . in all manner of things.

 

[Zebra]

Robgil is that you, showering in your kitchen sink? Gosh, and I thought my bathroom arrangements were rudimentary!

 

[LadyArowana]

Robgil is that you, showering in your kitchen sink? Gosh, and I thought my bathroom arrangements were rudimentary!

No, actually that's Penners..... ( it's how he got his bad back, but of course he doesn't like to talk about it ).