Grout cleaning

[SarfEast1cated]

Hi there knowledgeable people - can you help me with a grout query?
Ours is pretty grubby and I am borrowing a steam cleaner to try to clean the grouting, but if that fails I am wondering whether it might be quicker to just put another coat of grout on top?
Is that possible?

Spray it with dettol mould and mildew remover and leave to work for a while

We used Everbuild Forever White Grout Reviver Arctic White. You can get it on Amazon, it's not expensive. It was absolutely fab, it looks like new tiles. The reviews are really good!

We used Astonish mold and mildew remover, it's in a green spray bottle at home bargains and only costs £1 our grout was pretty nasty when we bought this house and we had to use the bathrooms till we can replace them. Spray it on and walk away for a while, keep using it and it;ll turn all the grout nice and clean.

Bleach and bicarbonate mixed to make a paste - leave overnight

I tried loads of things and nothing worked. It was easier to remove the grout and put new grout in. You can buy a pointy grout-remover tool, new grout in a tube with a nozzle, and a track gel tool for smoothing the new grout, from
Homebase.

Easily done, leave for 24 hours, looks fab 6 months later

Triangle tool, not Track gel!

We have quite a large area to treat and not much time... I wonder if we can get a nice man in to do it! Have my mum's steam cleaner so will try that tomorrow!
Thanks everyone :)

Bleach and bicarb in a paste is MAGIC. Paint on, leave for several hours, rinse off.

I use white vinegar and an old toothbrush. Mine was disgusting when i moved in.
Leave the vinegar to dry before having a bath. Then just wipe it off. I use window cleaner with vinegar to keep the tiles streak free and i think the continued little bits of vinegar use helps stop the build up.