How do I repair cracked grout?

[colin79ie]

I have white grout in a downstairs shower wher it has a small crack right the way from floor to ceiling in the grout itself, not the tiles.

What is the best way of repairing it as I would assume water can get in behind it, although it's a concrete wall downstairs.

Should I just grout over it again to fill the gap or try to pull it out and redo it?

 

[Sconhome]

You could rake out the grout and re seal with fresh fine grout or get waterproof caulk and fill the crack.

 

[iggy]

I would run a bead of silicone sealer down the full lenght of it.