Cleaning cold water tank in loft?

Hello, During the addition of more insulation in loft and around tank, I noticed that there was some rather nasty looking in scum on the water surface (brownish rather than green). I haven't felt the need to do anything about maintaining cleanliness of tank over last 25 years so am not rushing now but this does prompt me to ask whether it's a good idea to carry out some regular cleansing and if so what to use and how often might be appropriate? Tank is obviously going to be warmer than ever for the summer months and this could I suppose promote growth.
Any suggestions?
--
Colin Brook - Winchester (UK)
mailto: snipped-for-privacy@cbassoc.demon.co.uk
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Colin Brook wrote:

Drain it, clean it, flush it, fill it, and *put a proper lid on it* !
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Colin Brook wrote:

Best to put in a new Bylaw 30 compliant tank, with a tight-fitting lid, insulation, filtered air vent, overflow screen, etc. Probably less work than bringing an existing tank up to current standards. Tepid water and any contaminants will encourage the growth of bugs. Lofts can get very hot.
You can clean it out by siphoning out the contents. A 20ft drop will generate a powerful suction and you can hoover up any debris in the bottom of the tank with the hose end. You can start the siphon by connecting the lowest end of the hose to a mains tap, open the tap to send water up the hose to the tank & so getting all the air out of the hose, then disconnect from the tap & siphoning will start. Clamp the hose flat if you need to take the end outside. Works best with a helper. A properly installed tank will have no dirt in it, except maybe for some limescale.
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On Tue, 06 Jun 2006 04:45:47 -0700, Aidan wrote:

If you're lucky you may find a correct sized close-fitting lid for your existing tank.

What a palaver! Run your hose from somewhere outside (where the water can discharge to) up into the attic. Dunk several feet of it into the tank keeping it sloping down to the open end so that it fills with water as you go. Then block the open end (with your finger or fold the pipe or whatever works) and pull back most of the pipe and let it hang over the side of the tank, so that the several feet of water you've got trapped in the pipe is mostly outside the tank. Unblock the end and the syphon will start.

Easily do-able by one person!
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John Stumbles wrote:

For a 25+ year old tank? I once tried finding a lid for a tank that was 6 or 7 years old. Complete waste of time, no lid available would fit; it needs to be within a couple of mm to get the snap-on tight fit. Tried the makers, they said the lid supported the tank sides and they would have distorted. If I'd found the right lid ( tank was no longer made) it wouldn't have fitted. I'd been asked to investigate problems with blocked water pipes, turned out to be bits of loft insulation that had got into the tank and were plugging the pipes at the reduced-bore service valves.

Worked for me, dear.
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On Wed, 07 Jun 2006 01:41:50 -0700, Aidan wrote:

Yeah I know it's a long shot (I did say "If you're lucky") but worth checking. I actually found one that fitted a tank I needed a lid for the other day - that was sweet!
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John Stumbles wrote:

He could also *make* one.... DIY it...
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Chris Bacon wrote:

Considered that.
A pukka lid is an ornate moulding with a continuous lip inside the tank edge to shed condensation. A flat sheet of say perspex would sit neatly on the tank, but the condensation would would make contact with the tank and would escape, saturating the insulation. This had caused the problems with the tank I referred to. A flexible sheet of polythene, say, might fall towards the centre of the tank and so avoid the escaping damp problems, but you would have an unpleasant job trying to make it airtight (gaffer tape, bungees?) in a restricted loft space. The splashing around the float valve will find any opening. The first time someone removes it, to service the float valve, it will get chucked in a corner; lazy plumbers do that with proper tank lids anyway.
This country has a long tradition of grotty water storage tanks with grotty pikey lashed-up lids. Most people wouldn't leave a saucepan uncovered in their kitchen for fear that dust would settle in it, so why be any less hygenic with the water? A proper tank with a proper lid; there's a satisfying clunk as the lid snaps securely into place.
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Aidan wrote:

A sheet of WBP is a good start.... it doesn't need to be airtight, just to stop "dust" getting in.
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Chris Bacon wrote:

BTDT. Unlikely the tank, and the lid, will be exactly level. Condensation droplets & splashes on the underside of the lid runs down the sheet of WBP until it reaches the tank/lid junction. Capilliary action draws some of it through the joint, saturating the tank insulation and making a damp patch below.
New tank; 60? Less work involved in fitting a new tank than in flaffing about with it. WBP probably not permissible under the Water Bylaws.
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Aidan wrote:

It shouldn't be far enough off to matter. The tank should sit on a flat base.

Sounds as though the tank or weren't installed properly in the first place.

70 from Screwfix for a 50-gallon tank, or 86 for 2x25 gallon ones (which gets you, effectively, a spare set of "bits"). Quite possible that getting a new tank or tanks would be best.

Nevertheless, it works well (in most cases).
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Chris Bacon wrote:

No one's going to check it's level, but just whack it onto a base of WBP on 3x2's on the joists. You can get something like 1/2 pt of water running off the underside of a tank lid when you open it. A WBP lid would probably be bowed one way or another and you'd probably get some water leakage.

It wasn't; they hadn't fitted the lids that had come with the tanks. New houses, I think all were like that; probably they'd mixed mortar in the lids. The loft space was restricted (roof trusses) & me a bfg. It was a virtual avalanche of unpleasant jobs caused by the omission of the tank lids some years previously.

Certainly better than nothing. Having done it once, I'd just get a new tank if I had to do it again.
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On Wed, 07 Jun 2006 08:05:29 GMT, John Stumbles

Am I missing the point here? Why not tie-up the ball-cock or, if won'es fitted, turn off the ervice valve in the cold water feed to the tank (unlikely to be there for an old insallation of course) and then drain the tank through a tap that's connected to the tank? Tim Hardisty. Please remove HAT before replying by email.
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Tim Hardisty wrote:

Could do, but there are disadvantages;
1) The outlet connections are usually through the side of the tank and 25 or 50mm above the bottom. Heavy particles (limescale, rust,) settle to the bottom of the tank and won't get into the outlet pipes. Floating particles (dead insects, leaves, etc) will go down the outlet pipes. 2) The resistance may be high (due to bends, elbows, tap outlet resistance, etc.,) and it probably won't generate flowrate & the mount of suction that a vertical, unobstructed hose will. Also you can't use the outlet pipes to suck up muck in the corners of the tank. 3) You do not want the muck in the distribution system. It will get into taps, mixer valves, washing machine & dishwasher solenoid valves, etc.. These things don't like solids; even if there are any strainers, designed to catch solid particles, you'd have to dismantle it to clean it out. It will also settle at the bottom (coolest part of cylinder and lowest water velocity in the piped system) of the DHWS cylinder, where it will stay and provide nutrients for any resident bugs, or provide them with a shelter from high pasteurising temperatures.
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Just a quick thanks for all suggestions. I think the new tank will probably be the best solution but I may need to clean the existing one as an interim.
Regards, Colin
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Colin Brook - Winchester (UK)
mailto: snipped-for-privacy@cbassoc.demon.co.uk
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