It brings back memories of the cycle (push bike)water bottles that used to be used (maybe still are used) they always tasted "funny" for that very same reason. I would think that care should be used when trying to treat this with some sort of cleansing medium (Vinegar comes to mind)as the acidic nature of these may rot it further? anodising also springs to mind but How and at what cost? how about cutting a trap and then using water tank paint (plastic coat sort)or a bag filler in some sort of Poly, speak to Tek tank
Best of luck. if it is possible someone here will know!
Last fall I took out the water tank (hell of a job, they seem to take a water tank and build the boat around it) as it had a very tiny leak.
Took it home and opened the inspection lid. Found the white-yellowish stuff you mention. The grain size is like sand. I flushes it all out with the garden hose.
I am also not sure what it is. The tank did show some pitting corrosion inside but I could not relate it to the deposit in that sense, that the deposit was not specifically in the areas of the corrosion.
Had the tank welded and replaced it. Hope it lasts another couple of years.
Anyway, I am glad it wasn't the diesel tank...
The white stuff is probably caused by a reaction between the chlorine (added by the water board) and the aluminium tank
I have an aluminium water tank and initially suffered from blocked taps and a clogged water pump.
The best way of preventing the formation of the white stuff is to filter all the water put into the tank using one of the oin line charcoal filters available in most caravan shops (and chandlers).
If possible it is worth emptying the tank and vacuuming out as much of the white stuff as possible and then ensure that all water is filtered as it is put in the tank.
It worked for me - no more clogged taps or filters.
I believe the white stuff is an oxide of aluminium formed when aluminium chloride is reacts with water.
Mailspeed sell one called 'Freshness' at £31 (page 132 of catalog) also one called 'Aquasource Clear' at £17 - They are a cylinder about 1.5 ins dianmeter and 10 in long with a spigot at each end for atatching the hose pipe.
Will probably be cheaper at a caravan shop. I renew mine each year.