Plumbing advice

southcoastrgi

Most comments are very good advice, however one thing that no one has mentioned is that where pipes connect to (most taps & ball/fill valves) they are sealed by a fibre washer, this works by getting wet & swells up, now these washers will have dried out & that could lead to these connections to leak, I would check all these connections including the bath, also are you sure the gas is still connected as they may have disconnected it after 12 months of no use 

Another_Level

Yes as above, be prepared for the water leaks 

Float operated Ball valves may have become stiff or the rubber seal washer perished. Check tanks or cisterns dont overflow.

After running off some mains water, pour some into a clean glass. Is it clear,drinkable, smelly ?

If your getting a gas tech to service/test the gas appliances/installation, maybe ask them to recomision the complete water system  

  

Bendy_House

calvincamel said:

 See above, it's a vented system(! I've learnt a bit from quick research) - boiler/cyclinder/cold water cistern.

With all outlets (taps, toilet flushes, cold water cistern) closed, air pressure in the pipes stop water from flowing freely, unless there is a leak - is that the idea?

Thanks for the info cc.

Yes, that's the idea - by leaving the taps off when you open the stopcock, you'll know the resulting flow will be due to either refilling the CWS, refilling toilets, or a leak.

You've described the system - back boiler, CWS in the loft (along with a smaller F&E tank which is/should be nothing to worry about in this context as it's a separate water content), and a vented hot cylinder.

Are you able to go and assist with this 'commissioning'? You know far more than most about the 'medical risk' part, so all I can do is suggest an approach to the 'technical' side. If you think, for example, that chlorinating the CWS is a good approach, then you are a better judge of this than me. If you have realistic concerns about the state of the water, then that could well be a sensible approach, so that would override anything I say, which is just based on what I would do under these circumstances.

The main component in the whole system that's worth physically investigating is the CWS. If you can have a look at the water content of this with a torch, you'll have a very good idea of the state of the whole DHW system. If the water is clear, then I'd just tie up up the ballvalve to stop it refilling (or shut off the inlet valve to it if there is one) and run a hot tap until the CWS is empty - you'll now have drained away all the cold stored water except what's left in the pipes.  Give the tank a good clean with antibacterial liquid, and let it refill.

When it's reached at least half-way full, you can start opening taps in turn and letting them each run for a good minute or so, both hot and cold. This should have the fresh water from the clean CWS flushing and filling the system, including the hot cylinder.

Then turn on the immersion heater and/or the back boiler, and get the hot cylinder up to 65oC+.

That's what I would do.

If you know of suitable chemicals that could be added to more effectively do this job, or just make it more certain, then that sounds good.

Could you report back, please, as this could be useful info for others?

(You will also be more clued-up than me about standard safety procedures like what type of mask to use when running taps etc.)

Section62

Bendy_House said:

The main component in the whole system that's worth physically investigating is the CWS. If you can have a look at the water content of this with a torch, you'll have a very good idea of the state of the whole DHW system.

Looking at the water won't achieve very much.  Bacteria are too small to see with the naked eye, and any 'sediment' type contamination will have settled out a long time ago.  The water can look entirely clean, but still harbour dangerous pathogens.

Visual inspection will only pick up any gross contamination - for example dead pigeons.

Bendy_House said:

If the water is clear, then I'd just tie up up the ballvalve to stop it refilling (or shut off the inlet valve to it if there is one) and run a hot tap until the CWS is empty - you'll now have drained away all [1] the cold stored water except what's left in the pipes.

For reasons I gave in my previous post, it is best to avoid (if possible) introducing 'old' water from the cold water storage tank into the hot water system.

If there is no isolation valve between the cold water tank and the hot water cylinder the next best thing is to keep the hot taps closed to minimise the amount of water entering the hot water system from the cold water storage.

Instead, run the cold water tank down (and flush it, see below) via a cold tap supplied by the storage tank. If there are no such cold taps then try the toilets, or use the drain-off [male chicken] on the supply-side of the hot water cylinder.

[1] - Otherwise the hot water cylinder will still be full of stored 'cold' water drained out of the cold water tank.

Bendy_House said:

Give the tank a good clean with antibacterial liquid, and let it refill.

Using any kind of cleaning liquid in a cold water storage tank is inadvisable, unless it is marketed specifically for that purpose - and that really is a job best left to a professional.

Contamination of the water from a badly chosen cleaning product could pose more of a health risk than whatever might be in the tank to start with.

Bendy_House said:

When it's reached at least half-way full, you can start opening taps in turn

It would be better to leave one or more of the taps supplied by the cold water tank open to begin with, so the outflow from the cold water tank (when the mains feed is restored) can be greater than the inflow.

That way the small residual volume of water will be flushed out of the system more effectively.  Adding half a tank of water before starting the drawoff will dilute the small residual volume into a larger residual volume which will then need to be cleared out.

Creating that larger initial volume of water to deal with is just adding to the problem.

Building up the volume of cold stored water should only start after the flushing has been completed and the system checked for leaks.

Bendy_House

Section62 said:

Bendy_House said:

The main component in the whole system that's worth physically investigating is the CWS. If you can have a look at the water content of this with a torch, you'll have a very good idea of the state of the whole DHW system.

Looking at the water won't achieve very much.  Bacteria are too small to see with the naked eye, and any 'sediment' type contamination will have settled out a long time ago.  The water can look entirely clean, but still harbour dangerous pathogens.

Visual inspection will only pick up any gross contamination - for example dead pigeons.

Bendy_House said:

If the water is clear, then I'd just tie up up the ballvalve to stop it refilling (or shut off the inlet valve to it if there is one) and run a hot tap until the CWS is empty - you'll now have drained away all [1] the cold stored water except what's left in the pipes.

For reasons I gave in my previous post, it is best to avoid (if possible) introducing 'old' water from the cold water storage tank into the hot water system.

If there is no isolation valve between the cold water tank and the hot water cylinder the next best thing is to keep the hot taps closed to minimise the amount of water entering the hot water system from the cold water storage.

Instead, run the cold water tank down (and flush it, see below) via a cold tap supplied by the storage tank. If there are no such cold taps then try the toilets, or use the drain-off [male chicken] on the supply-side of the hot water cylinder.

[1] - Otherwise the hot water cylinder will still be full of stored 'cold' water drained out of the cold water tank.

Bendy_House said:

Give the tank a good clean with antibacterial liquid, and let it refill.

Using any kind of cleaning liquid in a cold water storage tank is inadvisable, unless it is marketed specifically for that purpose - and that really is a job best left to a professional.

Contamination of the water from a badly chosen cleaning product could pose more of a health risk than whatever might be in the tank to start with.

Bendy_House said:

When it's reached at least half-way full, you can start opening taps in turn

It would be better to leave one or more of the taps supplied by the cold water tank open to begin with, so the outflow from the cold water tank (when the mains feed is restored) can be greater than the inflow.

That way the small residual volume of water will be flushed out of the system more effectively.  Adding half a tank of water before starting the drawoff will dilute the small residual volume into a larger residual volume which will then need to be cleared out.

Creating that larger initial volume of water to deal with is just adding to the problem.

Building up the volume of cold stored water should only start after the flushing has been completed and the system checked for leaks.

Really? Bacteria are that small? Maybe that's why they remind me of something.

You visually check the CWS to see if there's a 'pigeon' in it, or any other obvious sediment or floaters, or whether it's visibly clean. If the latter, then there's no harm in also draining it via the hot cylinder as this will serve to start the moving-out of the hot cylinder's visually-uninspectable contents. Obviously, if the visual inspection of the CWS showed a pigeon or obvious sediment in the CWS, then you wouldn't do this - you'd have to find another way to drain the CWS depending on its 'contents'.

Provided the water going into the hot cylinder is visibly clean, then it's fine to use it to start the 'flush' - the shifting out of the hot cylinder's unquantifiable contents - and this will soon be replaced by fresh cold water to complete the job. In any event, the hot cylinder will ultimately be zapped by 60o+ heat, so Leggie will be killed dead.

Regarding the use of chemical cleaners, CC knows more about legionnaires than me and, I suspect, you, so I wasn't anticipating him pouring a keg of concentrated household bleach in there, but instead to use his knowledge to introduce the correct concentration of his chosen product, and then either neutralise it (Sodium Thiosulphate for Chlorine, anyone?) or simply ensure it's flushed through thoroughly. I wasn't going to patronise someone with such detail, when they clearly have a greater knowledge of this aspect than me.

CC seems to want practical guidance on the mechanics of this task, so I've tried to provide it, as simply as possible - not a single mention of a 'red wheel'. Coupled with this, I brought to his attention the option of him going 'chemical' on this, as he's very likely to be knowledgable in this department. So if he prefers to add a dollop into the CWS, and let this do its job - very probably the ultimate solution - then cool.

Section62

Bendy_House said:

Ho-hum, you visually check the CWS to see if there's a 'pigeon' in it, or whether it's visibly clean. If the latter, then there's no harm in also draining it via the hot cylinder as this will serve to start the moving the hot cylinder contents out - which you cannot inspect visually, and is unlikely to be in . Obviously, if the visual inspection showed a pigeon or obvious sediment in the CWS, then you wouldn't do that - you'd have to find another way to drain the CWS depending on its contents.

The basic principle of pollution control is to avoid spreading the (potential) pollution into places it hasn't got to, or unnecessarily* increasing the volume of contaminated material. (* the main exception being where the hazard primarily exists through high concentration and dilution will minimise the risk)

The cold water storage tank represents the greatest source of risk having openings to the atmosphere and the potential for activity by aerobic organisms as well as anaerobic ones.  The pipework and hot water cylinder by now likely only having the latter.

So, don't deliberately transfer 'pollution' from the dirtier storage (the cold water tank) into parts of the system which can be expected to be cleaner.  And particularly avoid contaminating the hot water cylinder because draining and cleaning those is a pain.

That's the "harm" of the approach you are advocating - and that approach offers no practical benefit (particularly not in this case) to offset the additional risks.

Bendy_House said:

Provided the water going in to the hot cylinder is visibly clean, then it's fine to sue it to start the flush, and this will soon be replaced by fresh cold water to complete the job. In any event, the hot cylinder will be zapped by 60o+ heat.

The really dangerous stuff is things you can't see (or smell). Hence the limitation in the value of a visual inspection.

So being "visibly clean" is meaningless if the aim is to minimise risk of adverse health impacts.  A systematic approach has to be adopted instead.

And 60 degree heat doesn't neutralise all the potential problems with contaminated water. Some contaminants are resistant to that level of heat (and much hotter).

Bendy_House said:

CC knows more about legionnaires than me, and I suspect you, so I wasn't anticipating him pouring a keg of concentrated bleach in there, but instead to use his knowledge to introduce the correct concentration of his chosen product, and then either neutralise it (Sodium Thiosulphate anyone?) or simply ensure it's flushed through thoroughly. I wasn't going to patronise someone with such detail, when they clearly have a greater knowledge of this aspect than me.

"Suspect"[ing] stuff is not very wise, just like assuming stuff isn't.

The OP might know about what chemicals it is safe to use, but the next forum member reading this thread looking for a solution to the same problem won't necessarily have that knowledge.

This isn't the first time in recent months that someone suggested using random cleaning products on a cold water tank, and that is really bad advice when the water could be ingested or come into contact with skin and eyes.  If flushing with mains water isn't sufficient (it probably is) then the tank really ought to be professional cleaned, or removed and replaced.

Bendy_House

Section62 said:

This isn't the first time in recent months that someone suggested using random cleaning products on a cold water tank,

And mine wasn't the second.

"If you know of suitable chemicals that could be added to more effectively do this job, or just make it more certain, then that sounds good"

Section62

Bendy_House said:

Section62 said:

This isn't the first time in recent months that someone suggested using random cleaning products on a cold water tank,

And mine wasn't the second.

"If you know of suitable chemicals that could be added to more effectively do this job, or just make it more certain, then that sounds good"

It was the following comment that I was referring to...

Bendy_House said:

Give the tank a good clean with antibacterial liquid...

With no caveat about making sure it was suitable for use in plumbing systems where the water could be ingested or come into contact with skin.