Old sheets needing a bleach - but what kind?

[festivalwidow]

After a significant water-tank leak above our airing cupboard, I now have a number of formerly white sheets that need a bleach.
I would usually take the approach of putting them outside on a sunny day and hoping for the best, but stain remover isn't cutting it and I think bleach is called for. Do I need special bleach to get rusty-water stains out, or will a good soak in a bucket with the generic 99p stuff do?
(ignorant emoticon)
Thank you, wise ones!

I would say bleach is bleach and wilkos cheap stuff would do fine.

rust stains tend not to come out. You can remove them with a special acid cleaner but I've never seen it done. They will fade over the next few years of washing.

Napisan could be good?

You could always try the bleach method and if it doesn't work, dye them a dark colour of your choice to cover the rust stains (or at least make them less noticable.
I've used the Dylon dyes in the washing machine with good results.