Hi I am hoping you may be able to provide an answer to the following problem. The guy who lives in the upstairs flat plumbed his washing machine into the rain water drainage pipe that leads down into the corner of my garden. I now know this illegal and have been promised he will stop using it. However, everytime he has done a wash it has flooded my block paving due to the pipe not being able to deal with such a large rush of water. This has turned my block paving white. Is there any way of removing this staining? I'm not sure whether it is staining or if it has bleached the colour from the paving blocks?
That white staining is probably a soap residue. It's not easy to 'bleach' coloured concrete using laundry products. The most obvious candidate, namely bleach itself, doesn't actually fade or whiten coloured concrete.
So, a soap removing chemical would be the logical answer. Vinegar, ammonia and sodium hydroxide (used individually, not mixed together, I hasten to add!) are the usual suggestions.