How do you clean the white grout in a shower without harming the grout in any way?

Answer

Mix up a paste of bicarbonate of soda and water. Best to use a paintbrush or something similar to paint the paste onto the grout. Leave for a few hours and then wash off. Grout should be sparkling white. For really stubborn stains, use the same paste on a soft toothbrush and some old fashioned elbow grease.

There is a product from Australia that is a broom on mop off grout cleaner no nasties www.pinkstuff.com.au