We've had issues for ages now with our water supply. The mains supply
itself contains sediment, but the hot supply is giving us problems we
are baffled by.

The worst problem is when more than one hot tap is opened and demand
is higher around the house. What happens is that fairly large
particles, which I can only describe as being similar in appearance to
snots (no joke!) flow out with the water. I've been wondering for a
good while as to what the hell this stuff can be. You don't really see
it with just one tap opened, or demand being lower, but its an
unpleasant thing to have in your supply right?

I've talked to plumbers, they don't want to know really (because I
presume they have no clue how such crap could form in the hot water
cylinder). Live in Dublin btw, and never seen this in any house but
mine. Would appreciate input, cheers.