Fresh Water tank

Hi,  I would appreciate some guidance on how to clean/sterilise the fresh water tank on my 2013 Broadway EKLT.  I'm not having any problems and drain regularly but I've read that the tank should be 'deep cleaned' periodically to stop build up of unwanted sludge, mould etc.  I've got no idea how to access or undertake this cleaning.

Thanks

M

I just purchased a 1litter bottle of sterilising fluid from a local shop followed the instructions on the bottle ran it through the taps (cold only) the just let it sit for a few hours. Then opened all cold taps ran it though in to the waste tank let it in there for a few hours. Filled it with fresh water ran that through the cold taps and emptied everything. Including boiler. That seems to have done the trick water tastes fresher now

We use Elsan Fresh Water tank cleaner, which works well. There are also  some other products available, one of which would be Puriclean.

Suggest you do a search on here. There are loads of posts - and opinions!! 

On my 2019 Nuevo its not possible to pump water from the fresh water tank without it filling or at least partially filling the Truma Combi's hot water tank.  Truma recommend the use of suitable commercially available products to clean, sterilise and maintain the boiler providing it does not contain chlorine.  I wonder if this rules out products like Puriclean and Milton?  The only advice given in the Auto-Sleepers handbook is that prior to use and at regular intervals, but at least every 3 months, the fresh water system should be flushed through with fresh water. For the waste water tank only Auto-Sleepers recommend the use of mild disinfectant.

Caraman wrote:On my 2019 Nuevo its not possible to pump water from the fresh water tank without it filling or at least partially filling the Truma Combi's hot water tank.

That is partially true.  If you close off the auto drain valve and turn the taps to cold then when you pump very little water will go into the hot tank.  But you are quite right that Chlorine spells death to stainless steel.  I have used Tescos baby bottle sterilising tablets in the past without noticing any leaks - yet.  However what I do then is to fill the tank without having switched on the water pump so no water at all will go into hot tank.  I then let that stand overnight.  Next step is to pump some water through the cold taps making sure that I don't turn on the lever towards hot.  That needs conscious effort as i leave the taps open midway between hot and cold over winter.  Once the water has spluttered out of the cold tap I close the taps, switch off the pump and then drain the fresh water tank. While that is draining I turn the taps to hot and open them and the auto drain valve.  That drains any water purifying water that may have managed to get into the hot tank.  Let the residual sterilising solution remain in the cold pipes overnight and then refill and drain the tank through the taps - cold and then hot to get the taste out of the system.  Sounds complicated but I think that it is logical and it is not as difficult as it sounds.  Van is 8 years old in May.

Thanks Inspiredron.  I think when I did it both the hot and cold taps were shut and then I could hear the hot water tank filling.  If the cold taps are open and the hot are shut, the water should go the easiest way which is though the cold taps rather than into the hot water tank.  I suppose the question should be asked how necessary is it to sterilise the cold water pipes and taps if the AS advice is followed to regularly flush the system with fresh water and of course drain it down afterwards if it is not in use?  AS recommend the best way of draining down is to take the motorhome for a short drive with the taps and drop valve open.  

maj_069's original question was how to clean/sterilise the fresh water tank to stop the build up of unwanted sludge, mould etc.  For this it should be possible to introduce a sterilising agent without it being pumped into the hot or cold water system.  My Nuevo's fresh water tank is fitted with a flexible drain hose that can be unclipped and lowered to help remove all water and residue from it.  If this is done in between periods of use I would have thought that the tank should remain reasonably clean.

That's what i do to drain.  On my Humer I used to get mould forming on the wide inlet pipe to the tank.

I have read of people using white wine vinegar, which is free of chlorine, to sterilise and remove lime scale but have no experience of using it in a motorhome or caravan.

Anyone remember Zappy's Tablets?

Zappy (Graham) was a water scientist of some kind I believe, and he supplied sodium hypochlorite tablets for tank cleaning. That's "bleach" by another name of course.

He also provided a dilution chart and detailed instructions on how to perform the cleaning process, which never caused any problems as far as I'm aware.

Sadly, due to ill health his website no longer exists, but someone will have a copy of his instructions and may be willing to post it. As I recall it specified the strength of his tablets and precise details of dilution rates, so it would be easy to adapt it to tablets from another source.

MelB wrote:


I simply buy citric acid from Amazon, a large 500g tub is a few pounds. Its a natural acid but doesn't leave the after taste/smells that vinegar can. Also as it comes in a powder you don't have to lug lots of bottles around, just mix it up in a watering can or old plastic bottle and pour it in the tank.

For say a 100 litre fresh water tank, how much citric acid powder would you use?

I use 500g at a time but I bought the 5Kg tub from Amazon.  I do it once a year.
Sadly, I can't just pour it in. I have to pump it in using the Whale system.  That means dissolving about 100g at a time in a 10 litre jerry using warm water and alternating the warm with cold to stop th eexternal pump from overheating.  First time I did not alternate and on the third jerry I heard the tone of the pump change slightly. Quick stop, dunk in cold water, wait for a few minutes and all was well again with lesson learned.

Another option is to fit an in line water filter .

Molly3 wrote:Another option is to fit an in line water filter .

I don't think inline carbon filters remove bacteria, viruses or limescale.  Better to keep the water system clean by regular flushing with fresh water, draining down after all periods of use and, if necessary, by periodic sterilisation and descaling.

fit a filter molly3 no .clean the tank yes

Just use Elsan ‘Fresh Water Tank Clean’ once or twice a year & add some ‘Elsil’ when you fill up each time with water, job done simply. 

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But we drink our fresh water!

I used to use Zappy's tablets, as mentioned by Gromit earlier in the thread.  I've also used bulk white vinegar - not white wine vinegar, acetic acid solution. We allow this to stay in the water heater, pump, pipes etc  overnight to descale.  I agree that citric acid would be better in case of worries about taste, however we don't drink water from the onboard tank supply; we fill a separate 5 litre container and put it through a Brita filter jug for drinking. 

I'm not suggesting drinking from the tank will do you any harm, we did that ourselves for years, but now we start off from and travel in some very hard water areas hence the filter to keep kettle and coffee makers clear.

inspiredron wrote:But we drink our fresh water!

So do we… 

Elsan ‘Elsil’ is just an additive to purify water & keep it fresh so it’s safe to drink, we use a small dose each time we fill up & use the Elsan ’Tank Clean’ which is left overnight before being rinsed out for cleaning of the system after any period of being laid up.

glyne lock wrote:fit a filter molly3 no .clean the tank yes

OK

There's a photo on this forum somewhere of the inside of my fresh water tank, showing it sqeaky clean.

If you only fill up with fresh mains water (not rain water) then I really don't see that there should be a problem.  It's dark in there, so I can't see mould being an issue; and if you only use fresh water, where would the sludge come from?

We keep separate small containers for drinking water, which we refill frequently.  This is really just because the fresh water in the tank might stay in there for a while and get stale-tasting.

Nick.

I have clear plastic hose that I use to fill the tank from a tap, guess what it is spotted black on the inside, so what is the tank like?
We do not drink the water, but do use it to clean our teeth and wash hands as well as washing up.

Got me thinking now.
---------
Richard

rgermain wrote:I have clear plastic hose that I use to fill the tank from a tap, guess what it is spotted black on the inside, so what is the tank like?

It can only be that the plastic hose has not been allowed to dry out in between use.  I worry about the Whale collapsible Aquasource pipe and connector used to fill our on-board tank.  I roll it up after use and keep it in a plastic bag so it never dries out and it gets less regular use than the rest of the water system as I sometimes fill the tank with the much shorter and easier to dry Whale Watermaster.  When I remember I use the insert to flush water through the pipe before I use it to fill the tank.

I always use the insert to run water through before filling the tank. I also generally run the site tap before connecting my hose to it.
Clear hose + dampness + time = mould.
Hoses that are opaque don't generally get mouldy and neither does the inside of the tank.