Cleaning/Sterilising Water Tanks

[mark1882]

Any advice as to what's the best way to clean/sterilise my water tanks and associated pipework would be appreciated.

The water direct from the tanks (without using the filter) tastes and smells ok and I have a Nature-Pure water filter and separate faucet but feel that I should give the system a bit of a clean out before we go to the Med and also have the means on board of doing it whilst in the Med in case we inadvertently put in some 'not so nice' water.

I have noticed some blackish stuff in the filler hose, (the hose is strengthened see through type) which I assume to be mould, which has probably been there since I bought the bought 18 months ago but has not caused a problem with the water but I would like to get rid of it as part of the cleaning process.

I have had people suggest, Milton or bleach or chlorine tablets/powder so any advice from forum members would be greatly appreciated.

Thanks

Mark

 

[VicS]

Any advice as to what's the best way to clean/sterilise my water tanks and associated pipework would be appreciated.

The water direct from the tanks (without using the filter) tastes and smells ok and I have a Nature-Pure water filter and separate faucet but feel that I should give the system a bit of a clean out before we go to the Med and also have the means on board of doing it whilst in the Med in case we inadvertently put in some 'not so nice' water.

I have noticed some blackish stuff in the filler hose, (the hose is strengthened see through type) which I assume to be mould, which has probably been there since I bought the bought 18 months ago but has not caused a problem with the water but I would like to get rid of it as part of the cleaning process.

I have had people suggest, Milton or bleach or chlorine tablets/powder so any advice from forum members would be greatly appreciated.

Thanks

Mark

Using Milton the following used to be on their website as advice for caravan tanks etc

"The recommended dose for sterilising a tank with Milton fluid is 30ml per 5 litres. Allow to soak for 15 minutes and then rinse out."

For sterilising drinking water use 2.5ml per 5 litres. The water is usable after 30 minutes but don't exceed the dose or your tea will taste foul.


For a large tankyou could use a thin domestic bleach but only at the rate of about 12ml/5 litre and rinse more thoroughly

 

[macd]

I suspect the OP has rigid tanks, but it's worth noting that Milton (or similar) should not be used in some flexible tanks as it attacks the fabric of the tank.

 

[Minchsailor]

Milton is just an overpriced mixture of normal bleach and salt. I just put a decent tot of ordinary bleach (unperfumed, obviously) in my tank on an occasional basis. Seems to keep it sweet.

If you want you can use hydrogen peroxide. It does not smell or taint.

 

[Hugh Foulis]

I do my boat tank at the start of every season as part of de-winterising. Half a bottle of Wilkos finest "Baby" sterilising liquid (about £1 for 500ml) in the tank and fill with fresh. Run each tap in turn until you can smell the treated water is coming through then leave to stand for about 1 hr. Then run the tank dry again through each tap but mainly through the galley cold and refill with fresh, repeat the flush through without adding any sterilant and fill with drinking water. If you do it this way then disconnect the filter or have a new cartridge available because the sterilant will destroy the old one.

 

[VicS]

Do you have any more information on that. I know Plastimo do/did say not to use chlorine bleach in their flexible tanks but i'd always assumed tank linings were polythene. Milton, domestic bleach and even even more concentrated solutions are supplied in polythene bottles!

Personally I have fairly regularly dosed the water going into my flexible tank with Milton and occasionally flushed it out with a more concentrated solution with no adverse effect that I am aware of in 30 + years.

Maybe not all tanks are polythene lined ??

 

[vyv_cox]

The chemical methods do not remove the black 'mouldy' deposits. Whether they are harmful or not I don't know but I like to remove them. Mechanical methods with detergent are the only option. I made an additional inspection hatch in mine so that I could brush the far end. I find a (new) toilet brush to be very effective. Follow the brushing with a dose of Milton, then fresh water flush.

So far as the hoses are concerned I suspect that replacement every few years is the only choice.

 

[Piers]

Any advice as to what's the best way to clean/sterilise my water tanks and associated pipework would be appreciated.

The water direct from the tanks (without using the filter) tastes and smells ok and I have a Nature-Pure water filter and separate faucet but feel that I should give the system a bit of a clean out before we go to the Med and also have the means on board of doing it whilst in the Med in case we inadvertently put in some 'not so nice' water.

I have noticed some blackish stuff in the filler hose, (the hose is strengthened see through type) which I assume to be mould, which has probably been there since I bought the bought 18 months ago but has not caused a problem with the water but I would like to get rid of it as part of the cleaning process.

I have had people suggest, Milton or bleach or chlorine tablets/powder so any advice from forum members would be greatly appreciated.

Thanks

Mark

For years, I've been sterilising our tanks this way.

Half fill the tanks. Add Milton using their sterilising dosage as if for full tanks. Fill the tanks. Open all taps, showers and outlets until you can smell chlorine in the water from each one. Fill the tanks again. Leave 24 hrs. Drain through with all taps, showers, outlets open until empty. Fill, and repeat. Final fill should be clear and sweet.

Been doing this for 12 years - no side effects yet....

 

[macd]

Do you have any more information on that...Maybe not all tanks are polythene lined ??

I know of the warning only from two flexible tanks I've had which carried it. One came with a boat; the other was made for me by a company which also made hovercraft skirts. The material was definitely not polythene, but a much more substantial woven fabric with some sort of coating. Afraid I can't remember the name of the company.

 

[VicS]

I know of the warning only from two flexible tanks I've had which carried it. One came with a boat; the other was made for me by a company which also made hovercraft skirts. The material was definitely not polythene, but a much more substantial woven fabric with some sort of coating. Afraid I can't remember the name of the company.

Mine was made by a company who made hovercraft skirts too. Air Cushion Equipment IIRC. Over thirty years ago

Its double skinned and AFAIK the liner is polythene. Maybe a woven fabric has a nylon or polyurethane coating ????

 

[macd]

Hi again, Vic.
Mine were both single-skinned so clearly different. I've spent the last few minutes with Mr Google and learned that the one I had made came from Hovercraft Consultants. It was branded as Duratank (and impressively durable in appearance). The fabric seemed rubberised rather than polythene-coated.
http://www.hovercraftconsultants.co.uk/

 

[captmikecoin]

Take a look at this website: http://zappysblog.co.uk . It's aimed at motorhome users but the same principles apply. I've done my tanks and hoses his way and I now have no smell from the pipes. The process does need repeating annually if you leave your boat unused for several months even with the tank empty.

Cheers,

Mike

 

[Bawdrons]

Hi,

I used Puriclean. I did it one day when I knew I was gong to be spending the day working on the boat. I mixed the crystals to the recommended strength and added it to the tank (which was about one quarter full) then filled up the tank. Left it for 4 or 5 hours whilst working on the boat. Drained, refilled, drained and refilled. No after taste and no "tank" smell.

http://www.ebay.co.uk/itm/PURICLEAN...EANING-100G-CARAVAN-CAMPER-BOAT-/261155528429

 

[VicS]

Hi,

I used Puriclean.

Also chlorine based.
As effective, therefore, as Milton.
The same possible problems with flexible tanks,

Probably similar cost.

Same result.

 

[nemodreams]

2nd that - Puriclean.

Had a very foul flexible v-berth poly tank. Tried everything, including bleach to clear it. It was out of the boat and really black. Puriclean worked a treat.

If you only really use tank water for cooking washing etc - add a couple of tsp of sodium Metabisulphate every time you refill. Not great for tea or coffee - but I never use tank water for that anyway. Faint smell of sulphur - but squeeky clean tank all the time

 

[rob2]

If you have a large enough inspection hatch, then dose the tank with bleach, half full and double strength and draw some through the pipes. Then on with the Marigolds and swab the inside with a cloth or sponge. Fill up and leave to stand for half an hour then pump out and flush through. If you have gunge though, I'd replace the hoses - you just can't clean them properly.

Rob.

 

[Mistroma]

The chemical methods do not remove the black 'mouldy' deposits. Whether they are harmful or not I don't know but I like to remove them. Mechanical methods with detergent are the only option. I made an additional inspection hatch in mine so that I could brush the far end. I find a (new) toilet brush to be very effective. Follow the brushing with a dose of Milton, then fresh water flush.

So far as the hoses are concerned I suspect that replacement every few years is the only choice.

Vyv, I had such a hose 3 months ago and poured warm bleach solution into it, then left it for a few hours before draining & flushing. All the gunge vanished and the hose was clean again, so worth trying warm/hot bleach solution.

I usually open inspection hatches and clean inside before splashing dilute vinegar around the tank. This is then pumped through the system, drained and some neat vinegar left in the tanks. Seems to work. Boat is in a hard water area at present so I also added neat vinegar to a full tank of hot water and left it cooling overnight before draining. Not part of my standard winterising as I've usually had soft water.

The aft tank vent is easy to see and always looks fine so I'd assumed the forward tank would be in the same condition. However, last year I happened to notice that the forward tank vent pipe ran slightly downwards so was worried that there might be a problem. I disconnected at the tank and pulled it out straight enough to see a short section full of gunge where water was pooling. Easily cleaned as mentioned above and hose moved a bit to make it uphill all the way to the vent.

 

[Mistroma]

2nd that - Puriclean.

Had a very foul flexible v-berth poly tank. Tried everything, including bleach to clear it. It was out of the boat and really black. Puriclean worked a treat.

If you only really use tank water for cooking washing etc - add a couple of tsp of sodium Metabisulphate every time you refill. Not great for tea or coffee - but I never use tank water for that anyway. Faint smell of sulphur - but squeeky clean tank all the time

I noticed you suggesting sodium metabisulfite (typo said metabisulfate). I also keep some on the boat as it has useful properties. If you use sodium hypochlorite (bleach) to clean something (e.g. pipes, plastic tanks etc.) you will be left with some bleach in the system. Don't worry about having to flush a dozen times, just flush once and add a little sodium metabisulfite solution to kill off the bleach.

You will probably be left with some metabisulfite and think that is almost a bad as bleach. You can certainly taste sulphite in solution even at extremely low concentrations (a few ppm if I remember) so will notice the taste. Fortunately, sulfite readily oxidises to sulphate and you can't taste that at low concentration (not even certain if you can taste it at high concentrations). Just filling an empty tank and leaving it for a short time will introduce enough oxygen and agitation to oxidise the sulphite.

Tip for the day: Get some sodium metabisulfite as well if you are planning to use sodium hypochlorite bleach. I expect most people know this but might be a few who haven't come across it.

 

[vyv_cox]

Vyv, I had such a hose 3 months ago and poured warm bleach solution into it, then left it for a few hours before draining & flushing. All the gunge vanished and the hose was clean again, so worth trying warm/hot bleach solution.

When I used a similar method on our tank it was not 100% successful. I needed to flush the tank several times to get rid of the chlorine smell and taste, so it isn't a method I would advocate for them. Probably worth trying for hoses but mine were 25 years old and deteriorating on the outside(!), so well past their sell-by date.

 

[KellysEye]

I used to use a quarter cup of bleach per 40 gallons of water and run the taps so the pipes are cleaned. Leave for 24 hours, flush twice then fill.