When I was a kid I lived in a house with at least 1,200 square feet of white tile with white grout and a mother who kept a spotless house. Every summer my sister and I had the pleasure of helping her stain every inch of grout (I wonder how many miles of grout that would be if it was laid out straight???) We hated it.
However, my husband and I bought our home a couple of years ago and I kept saying I hated the tile. As time went on I realized, it wasn't the tile (which was nice and neutral,) it was the dark, dirty, old grout. So I pulled out my mother's trick and it was transforming.
I am amazed I have NEVER seen this on a home improvement show. I sat watching one of these programs recently where they were trying to get a house ready to go to market and make updates for under $1,000 or so. The bathroom got the attention and they scrubbed and scrubbed the grout leaving the old tile and in the end, it still looked dirty. Had no one in their industry ever heard of staining grout?!
I warn you now, this is tedious, but it is cheap.
A nylon brush
Grout haze remover
Grout stain in your chosen color (I found this at Home Depot, but not Lowe's)
A couple of cheap toothbrushes (you want it to be a rectangle and flat, unlike the ones we buy for out teeth that can get into corners, look at kid brushes)
A few small damp rags
(Recommended but not required) A shop vac, knee pads
Step 1: Acid Washing Grout
Follow the instructions on your acid wash/haze remover which involved saturating the grout with water for an hour.
I warn you, this stuff is an etching solution, it essentially takes away all of the protectants on the grout leaving it open and porous. You DO NOT want to do this step and wait until next weekend to stain. Everything will seep right in.
Second, protect your eyes and skin. This is not some terrible smelling chemical like you might think, it is just effective.
I suggest after scrubbing with the wash, you shop vac it up and flush the floor again, followed by another shop vac. I have done this the hard way with a mop and bucket - trust me it is worth the investment in the ShopVac, it will cut your time by triple.
Step 2: Staining
You want to work in small areas. I suggest you put the stain directly on the toothbrush rather than on the grout as the instructions suggest. work it into the grout following up immediately with a wet rag to take it off the tile. Don't let this stuff dry on there, its a pain to remove.
Step 3: Seal
I skipped this step when I last did this and it needs to be redone 2 years later which is a real bummer. We never sealed as a kid, I am sure this is why we suffered the summer ritual every year. Sealing is cake, wait the allotted time, apply, wipe off. Voila.