Fresh water tank sterilisation

Otter Spotter

Otter Spotter

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FUNSTER in a PVC
I am sure that people will have ideas about this so question is, how do you sterilise your fresh water tanks after the lockdown?
I have a 90ltr tank, electric water heater which holds 6 ltrs and the cold water feeds through an inline filter before it reaches the kitchen tap.
SHMBO insists when we used to travel in the PVC, that we bought spring water for drinking or Kept site drinking water in a separate container which think is a waste of space and payload.
 
We drink our water. For sterilisation, we use supermarket branded steri-tabs (usually from the baby aisle), leave it a while then flush it through. We don’t drink the water out of the hot water tank, so don’t worry about it. Regularly heating the water to 60C should kill off any bugs anyway.
 
Forgive me, as I’m new I might start digging threads up again that I come across.

What are people’s views on drinking water from MH tank/taps? I assumed it’d be fine as long as it’s fresh, but I’m not sure how I’d define ‘fresh’ - a couple of days old? My OH thinks we should have separate bottled water apart from for cooking/kettle etc
 
Each to their own I say, I always drink from the tap. I flush it through once a year with Citric acid granules food grade and never had a problem but there are very diverse opinions on here so stand back and wait😊
 
Winger said:
Each to their own I say, I always drink from the tap. I flush it through once a year with Citric acid granules food grade and never had a problem but there are very diverse opinions on here so stand back and wait😊
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I’m expecting mixed responses too, I think I’ll probably drink it but I’m more worried about how long the water stays okay for once in the tank and I guess it can also get warm, but I’ve no experience yet 🙂
 
andrewellis127 said:
I’m more worried about how long the water stays okay for once in the tank and I guess it can also get warm, but I’ve no experience yet 🙂
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Don't know about others but when I come home after a trip away I don't run the taps to drain the 'old' water from the alkathene, earthenware and copper supply piping.
 
Mains water as part of the treatment process may have a miniscule dosage of chlorine (it must be negligible so as not to be harmful when water is drunk), and that is much less than would be used in a swimming pool. The residual chlorine in mains water will be sufficient to keep it potable as it travels through the closed pipe network to your kitchen tap (if your area still has a lead main supply connection pipes, I'd be flushing through if it had been standing after a week away). But that trace of chlorine isn't going to be sufficient to ensure potable quality water once it's gone into an open system, such as properties that retain loft tanks (loft tank regulations have improved, but many were quite nasty without lids allowing all sorts of things to fall in). Hence advice only to drink water from the kitchen tap which was on the mains and not other taps that would be off tanks. It is actually recommended that water tanks and associated pipe systems are periodically sterilised, which rarely happens in the domestic home, but for larger buildings like hotels where they have health and safety duties that will be a regular occurence.

In a motorhome the situation will get a little more complex and so the trace chlorine, adequate to maintain potability in a sealed pipe system, may not be adequate for an open system. First there is the fill, often off hoses, sometimes from containers. How clean are those especially if they've not been used for a while and some water was left standing? As we fill, you've removed the filler cap, allowing potential dirt around the filler to fall in. But critical will then be the way the water is being stored. Many MH tanks, especially during summer will get quite warm. If water is allowed to stand for a few days, now it has been exposed to the gunk from those hoses, containers and even filler cap removal, the warmer temperature could be ideal for the bacteria to multiply. Keep it truly cold and you are probably OK. Commercial hot water systems are usually set to 60 deg (which is why you get all those hot water warning stickers) as that is needed to kill off bacteria like legionella.

So bottom line, there has to be a small risk at drinking water from your MH tanks. But it is also probably quite low if you've been careful how you fill. It may also depend on how healthy you are whether you can absorb a few bugs. For me I'll sterilise the tank once or twice a year, using a MH compatible solution (some chemicals including Milton fluids may actually risk damage things like on board boilers). I'll happily wash my teeth, and boil the tank water for cups of coffee. But if I want a glass of water, that will come from a mineral bottle in the fridge.

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Kannon Fodda said:
But that trace of chlorine isn't going to be sufficient to ensure potable quality water once it's gone into an open system, such as properties that retain loft tanks (loft tank regulations have improved, but many were quite nasty without lids allowing all sorts of things to fall in). Hence advice only to drink water from the kitchen tap which was on the mains and not other taps that would be off tanks.
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Very informative, thanks.
:unsure: Maybe I should sterilise my open loft tank which I've only looked into about twice in 37 years and then only when replacing the ball valve. The water from it supplies all the upstairs needs, (cold direct from it and hot via the copper storage cylinder) so I must swallow some when brushing my teeth and showering.
 
Unless I'm draining down for the winter I don't bother when returning from a trip. However part of the prep for a new trip is to fill the tank, flush through the taps, boiler etc then drain. Finally refill with fresh.

In 11 years we've had no problems appertaining to water. The tank gets used for everything except for cold drinking water, where we prefer bottled although I have been known to takr a glassful withut ill effect.

Incidentally, pre-prep also includes heating the hot water to 60 deg for an hour - after that the low setting is hot enough for us unless we intend showering. Using the higher setting gives us more hot water to shower with (more cold, less hot).
 
Spriddler said:
Very informative, thanks.
:unsure: Maybe I should sterilise my open loft tank which I've only looked into about twice in 37 years and then only when replacing the ball valve. The water from it supplies all the upstairs needs, (cold direct from it and hot via the copper storage cylinder) so I must swallow some when brushing my teeth and showering.
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Changing the subject slightly (but Funsters are good at that), modern regulations require roofspace cold tanks to have close fitting lids, if not fully enclosed, the overflow should have a mesh to prevent insects climbing in, and they should be fully lagged (to prevent heat as well as cold). If you've been at your home for some 37 years, I doubt your roof tank meets current water reg standard unless you had reason to replace it. The things I've seen in some tanks would make you shudder.
 
andrewellis127 said:
Forgive me, as I’m new I might start digging threads up again that I come across.

What are people’s views on drinking water from MH tank/taps? I assumed it’d be fine as long as it’s fresh, but I’m not sure how I’d define ‘fresh’ - a couple of days old? My OH thinks we should have separate bottled water apart from for cooking/kettle etc
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Ours is always fresh because I drain off any remaining water before refilling. How long do you run the tap water when you get home to flush the stale water out of the supply pipe to the house? Bet most never consider that.

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Kannon Fodda said:
Changing the subject slightly (but Funsters are good at that), modern regulations require roofspace cold tanks to have close fitting lids, if not fully enclosed, the overflow should have a mesh to prevent insects climbing in, and they should be fully lagged (to prevent heat as well as cold). If you've been at your home for some 37 years, I doubt your roof tank meets current water reg standard unless you had reason to replace it. The things I've seen in some tanks would make you shudder.
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Never come across a cold tank that supplied the cold taps in any of the houses I've lived in, the cold is always plumbed from the rising main. I know it happens in some parts of the country.
 
As some others, we use Puriclens a couple of times a year. We also have a Brita filter jug in the fridge for drinking and especially tea, often drawn from the standpipe rather than the ‘van tank.
 
Kannon Fodda said:
Mains water as part of the treatment process may have a miniscule dosage of chlorine (it must be negligible so as not to be harmful when water is drunk), and that is much less than would be used in a swimming pool. The residual chlorine in mains water will be sufficient to keep it potable as it travels through the closed pipe network to your kitchen tap (if your area still has a lead main supply connection pipes, I'd be flushing through if it had been standing after a week away). But that trace of chlorine isn't going to be sufficient to ensure potable quality water once it's gone into an open system, such as properties that retain loft tanks (loft tank regulations have improved, but many were quite nasty without lids allowing all sorts of things to fall in). Hence advice only to drink water from the kitchen tap which was on the mains and not other taps that would be off tanks. It is actually recommended that water tanks and associated pipe systems are periodically sterilised, which rarely happens in the domestic home, but for larger buildings like hotels where they have health and safety duties that will be a regular occurence.

In a motorhome the situation will get a little more complex and so the trace chlorine, adequate to maintain potability in a sealed pipe system, may not be adequate for an open system. First there is the fill, often off hoses, sometimes from containers. How clean are those especially if they've not been used for a while and some water was left standing? As we fill, you've removed the filler cap, allowing potential dirt around the filler to fall in. But critical will then be the way the water is being stored. Many MH tanks, especially during summer will get quite warm. If water is allowed to stand for a few days, now it has been exposed to the gunk from those hoses, containers and even filler cap removal, the warmer temperature could be ideal for the bacteria to multiply. Keep it truly cold and you are probably OK. Commercial hot water systems are usually set to 60 deg (which is why you get all those hot water warning stickers) as that is needed to kill off bacteria like legionella.

So bottom line, there has to be a small risk at drinking water from your MH tanks. But it is also probably quite low if you've been careful how you fill. It may also depend on how healthy you are whether you can absorb a few bugs. For me I'll sterilise the tank once or twice a year, using a MH compatible solution (some chemicals including Milton fluids may actually risk damage things like on board boilers). I'll happily wash my teeth, and boil the tank water for cups of coffee. But if I want a glass of water, that will come from a mineral bottle in the fridge.
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This is mostly correct. The chlorine levels in tap water varies in different areas though. It might be as low as <0.1mg/l . If you wish to increase it Tesco's thin bleach is ok as it has no additives. It is about 5% sodium hypochlorite. You will only need about 1ml for the whole tank. You could use a cupful and then drain it after 24hrs and refill. Put the bleach in first then fill with water.Don't use any thick bleaches as you will get awful tastes and bubbles. These have detergents in.

If you never clean your tank you will get a build up of biofilm. Harmless but unpleasant.
 
I don't think reassurance is necessary so long as you are not drinking the water from the tank and e expecting a pleasant experience. Bottled water however is a completely different matter. Bottled water is sterilised with UV light before being bottled and sealed. Your water tank has none of those things.

Water from your household tap is not sterilised. It has been disinfected to remove harmful bacteria, viruses and pathogens. It contains harmless bacteria and organic matter. These provide a food source. Over time a slime will grow in the tank, much the same as it does in a hot water feed tank. It's not an issue if you just want to use the water for washing, cooking etc, but if you want it drink it or make tea it will taste strange. Wont harm you though.

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The tank and pipes we flush through with puritabs after storage. We have a separate drinking water tap with a 3M filter system. The tap was already in the motorhome when we bought it but the existing American filter was around 100 pounds to replace and there was no spec on the company page regarding the actual size it filtered down to. The 3M system was 40 pounds for the housing and bypass plug and 55 for the filter. Filter should last us a year at least and we don't need to worry how potable the local potable water we load is.
 
nicholsong said:
Can any nasties survive in a drained-down system in winter?

Geoff
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Yes they can in theory, unless you can get it absolutely dry which is virtually impossible. Bacteria needs moisture. It also needs a food source. I wouldn't worry about it though, it's better than leaving it part full.
 
A bit of dirt in your system when a kid will prepare you for drinking dirty water later on. We drain down every time, flush once a year now with citric acid. Drink the water and we're still here.
You should be more worried if you go into take aways and cafes or use those petrol station coffee machines.
 
I ran out of Puriclean during lockdown and saw this on Amazon (Pro-Kleen Fresh Water Tank Cleaner)

It's a liquid so no tedious stirring to dissolve the Puriclean granules. Used on our brand new van and left it overnight, seems to have done the trick, no after taste after 2 rinses, although I might have to do it again when we finally get the chance to go away in it ! I've always drank water from the tank and will continue to, never had any ill effects.

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Why not just use tesco thin bleach. It's about 50p
 
thebriars said:
Never come across a cold tank that supplied the cold taps in any of the houses I've lived in, the cold is always plumbed from the rising main. I know it happens in some parts of the country.
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(Only just spotted this July post).
All the cold taps at the sinks, baths, showers and loo of my two upstairs bathrooms in my 1896 house are fed from the open galvanised steel cold water storage tank in my loft. As far as I can see all the plumbing except the showers is original .
 
Kannon Fodda said:
I'll happily wash my teeth, and boil the tank water for cups of coffee. But if I want a glass of water, that will come from a mineral bottle in the fridge.
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This

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