Puzzled - Water Supply

[davebro3]

For years ( yes literally YEARS) my water supply has left black streaks in the toilet after 3 or 4 flushes & sticky black deposits in the tap filters.

I have complained about this to Severn Trent a number of times with no joy - "Oh we have flushed the mains, it must be bio-film".

For the past 2 weeks it hasn't happened.

I'm puzzled - can anyone cast any light?

[barry1010]

My first (and only) thought is a water pipe that was causing the contamination has at long last been replaced.  

[davebro3]

there's been no digging locally tho'

[davebro3]

The only thing I can think of is that there is a new estate under construction about 1/2 mile away & that we have been switched to a new supply further up the chain.

[barry1010]

Needn't be local enough for you to notice roadworks, you could be right about the new supply.  Hope the change is permanent

[Old_Geezer]

Whether it was bio-film or something else, isn't the supplier under obligation to ensure they aren't delivering it to the public ?