Tim+ wrote:
Well, I finally got around to disconnecting the pipework from the top
of the tank the other day and tried syphoning the water out with a
hosepipe to see if I could drain the mud from the bottom of the tank.

This didn't porduce the expected results so I assume that the hose was
coiling up in the tank. I found a bit of 15mm plastic pipe which
made a perfect "dip-tube" to reach to the bottom of the tank and
started syphoning again.

Again, there was hardly any discolouration.

Having drained of a good deal of water reassmbled everything and
repressurised the system, I just flushed all the hot taps for at
least half an hour each.

This produced some crud briefly but then the water ran clear.

Despite all this, I'm *still* getting some discolouration when first
openning a tap in the morning (shower and bathroom sink) . It's
probably a bit less marked than it was though. I think just *has* to
be silt in the pipework but it's proving very hard (and slow) to
shift completely. :-(
I guess in time it will just clear up and I suspect it's the higher
flow rates induced by having a mains pressure tank now that is
shifting all this old crud but I'm amazed at how persistent the ruddy
stuff is! The tank was installed over a year ago and the problem has
been going on all this time.

We've been scratching our heads over this for months and having ruled out
sludge in the tank and contaminated mains, I had decided that it had to be
rotting stainless pipework. (There's a lot of it about in houses in our
area).

Anyhow, I was resigning myself to lifting floors, changing pipes etc. when I
thought I'd have a last look at the pipework in the loft and it was only
then that I realised that we had a very large dead leg of SS pipework in the
loft (and leading back to the tank). This had been rendered mostly
redundant a few years back and other changes to the plumbing at another time
had rendered it totally redundant. Because the work was done at different
times by different people, I don't think anyone had realised that this leg
was now dead.

Anyhow, it's now removed and problem solved (I think). ;-)

Tim