Re-grouting old tile is a time-consuming job, but it can help your floors look brand new again if done correctly. Here are a few brief guidelines you should follow when re-grouting tile that will help make the job easier and less overwhelming. First you will need to remove the old grout with a grout saw (available at most hardware stores and inexpensive.) Once the old grout is completely removed, it is time to mix up your fresh batch of grout according to the brand’s instructions. You will want to let it sit for a few minutes before using it. While you are waiting, you can gather your other materials. Mix the grout one last time, and then scoop out your fresh grout from the bucket and place it in the seams of the tile. Use your float to smooth it out and make sure it looks good and level. Immediately wash off any excess grout from unwanted areas with a moist sponge. Let it sit for a few seconds and then move on to a new area. More here