Cruddy cold water tank

[Dave]

As header. I have a cold water tank in the loft, that has a layer of black gunge on the bottom. I found this out cos the tank fed taps in the house are showing signs of the same gunge.

The question is...

How should I get rid of the black gunge?

A gallon of bleach in the tank, let it soak for a while, let it into the various tank fed cisterns / systems. Then turn off the cold feed and let all the water out of the system, fill it up again and drain off several times, to get rid of the bleach. Or is there an easier way?

Dave

[Ian Stirling]

Consider where the gunge comes from - it's probably in the water. I cleaned out the tank by the simple expedient of a long handled brush, and swirling it round the nearly drained tank. Flush it several times, and it was sparkling.

[Steve Walker]

The bleach will just turn it white....

My suggestion (but I'm no expert) would be to set the nearest tap open, and then start scrubbing away at the inside of the tank with a stiff handbrush. Theoretically you'll have mucky water pouring out and clean water coming in, so after 10 mins it should be pretty good. Then an overnight soak with a cup or two of bleach in it just to kill off anything left.

Don't do this until you've seen other replies - it might be a very stupid idea....

[Ian Stirling]

Turn off the input first. Otherwise you end up working deep in cold water. Then just follow the water level down going round the edge with a brush. End up swirling it round, then turn the input back on.

[Alan]

Definitely the water - I had this in my previous house which had a loft CW tank. As well as the gunge I had what looked like a few bucketfulls of sand in the bottom. Taps fed from the tank used to regularly eject gunge, and the cats' water fountain which was filled from the bathroom taps (don't ask, fussy cats didn't like the high chorination in the mains water) used to get gunged up regularly too.

Thing is, when I moved to a house with mains cold water only, I still get the black gunge forming on shower heads, taps and the cat's fountain so in my case it's definitely in the water.

I'd just leave it - it'll only come back again anyway. You could use a less dangerous way to sterilise it, like Milton.

[Ian_m]

Or get a water softener. They often have filters in to remove crud, which is backwashed down the drain during recharge, leaving clean, soft water to the tank in the loft. I emptied my loft tank and used a wet/dry vacumm (Earlex..) to vacumm the crud out the bottom shortly after fitting a softener. No crud has returned in last 18months.

[Dave]

Yes. I always thought that was where it came from.

I think I will go along the lines of a brush and see what happens.

Many thanks to all

Dave

[Andy Hall]

Don't knock it. Water fountains encourage cats to drink more water, which is no bad thing. Having said that, one of ours likes to dab the water out onto the floor so it's a constant battle to keep it topped up and mopped up.....

[Chris J Dixon]

Depending how viscous the gunge is, you might be able to siphon it out. Just get a nice long hose, run it out through a window, persuade a hapless accomplice to suck briefly on the end, then you can use it to "hoover" the bottom of the tank.

Chris