What does deposits on the fittings mean in practice?
A white deposit usually indicates hardness, while a rusty or black deposit requires checking for iron, manganese and the condition of the pipes.
When does it matter?
The type of sludge determines the technology; a mechanical filter does not remove dissolved hardness.
Which solutions are related to it?
Determine hardness, iron and manganese, and then select softening, iron removal or particle filtration.