New grout is quite different colours throughout, any reason?

[Mattyc123]

Hello, I laid these porcelain tiles and the first attempt for grouting was far too white. I since raked this out and replaced with the pictured grout.

On both occasions, the grout is a very different colour along the lines varying from what it should be, to a much darker tone as if it were wet. I used bottled water for the grout, but wondering if washing down with tap water (which is very hard where we are in London) could impact it in this way and to this extent?

Need to understand as I’m about to do the whole shower wall and would hate for it to end up looking bad/dirty.

 

[HarryL1234]

Nice tiling job, grout looks fine. Probably nothing more than the lighting. Just for info, most bottled water is hard water (if you look at the composition where it's provided, you'll find bottled water usually contains lots of Ca and other minerals). The exeption is bottled rainwater, which is not common in the UK.

 

[Mattyc123]

Nice tiling job, grout looks fine. Probably nothing more than the lighting. Just for info, most bottled water is hard water (if you look at the composition where it's provided, you'll find bottled water usually contains lots of Ca and other minerals). The exeption is bottled rainwater, which is not common in the UK.

Thanks for the response - definitely not just lighting but appreciate it’s not that obvious in the images. Either way doesn’t sound much like there’s an obvious reason/way to prevent it?! Good point about the water