Hot water tank - white residue

funkey_monkey

Does this need a plumber visit? No visible signs of a leak. It's on top of a hot water tank at a relatives house.

funkey_monkey

Bump.

Anyone?

10-10-20

I'm guessing it's a calcium / limescale build-up but unsure of the method of deposition here! I don't see copper-staining, which makes me wonder why the copper isn't corroding.

Can you describe the substance please?

Is it a hardened substance which cracks off, or is it soft and fluffy?

Does it originate from copper pipe and is there a leak at that point?

Are you in a hard or soft water area? Do you get similar furring on your kettle or around taps?

If you take a sample and drop it into vinegar, does it fizzle up after a few seconds?

funkey_monkey

Soft fluffy dry powder. No leak that I can detect.

Don't know if it is a hard or soft area, as it is a relatives house.

10-10-20

Can you even tell us if its a limestone area?

At a guess it's calcium carbonate which is forming from a leak at the pipe joint. It's creating that light crystalline structure because the water is possibly being wicked away from the leak through capillary action. The water is then being evaporated rapidly due to the heat from the tank. The crystals which rapidly form grow upon the structure of the existing calcium carbonate, and being small and weak and suffering from thermal cycling, break off and fall onto the copper tank as a dry chalky residue.

Fix the leak.

funkey_monkey

Just checked a website and it is cleared as moderately soft.

Calcium Hardness (mg/l) 37.2

Magnesium (mg/l) 4.1

Potassium (mg/l) 0.5

Calcium (mg/l) 30.3

Total Hardness (mg CaCO3/l): 92.8