how do you clean grout in tiled bathroom

[Eidel]

As the title says how do you clean grout in tiled bathroom, i've noticed some horrible black grout on our bathroom tiles and i have no idea how to get rid of it?

Thanks

Evil mould and mildew bleach spray..leave on, then scrub off. We've inherited a bathroom with pwrticularly bastardly mosaic type tiny tiles. Shower is particularly tricky. I tend to attack it in (in the nude) after a shower and rinse/scrub off in the evening.
When/if finances allow, new bathroom will have the most massive, small spaced tiles possible.

Dettol Mould & Mildew or the HG equivalent.

How smelly is the dettol spray? We have a bathroom with no window and I generally can't stand those sort of strong cleaning fluids. Vinegar won't cut it, I guess?/

Have a spray bottle with 50%distilled vinegar 50% water, spray it on the grout and leave it for about five minutes make a pasta with baking soda and warm water, dip an old toothbrush into it and scrub the grout, spray every so often with the vinegar, when clean rinse with water

I usually use bleach and scrub with an old toothbrush then rinse

Cool. I'll do that first Amalfi.

The Dettol is strongly bleach smelling. I spray it wildly, run away and open all the nearby Windows and leave it to work. Come back 30 mins later and rinse woth cold water and run away again.

Three parts baking soda to one part bleach mixed together into a paste and rub on with an old tooth brush. Leave for 5 - 10 mins and rinse off. It's magic!