CAN HARD WATER MAKE BLONDE HAIR BRASSY/

Yes Mineral such as iron and copper can contribute to oxidation, causing blonde to develop yellow, orange, or dull tones more quickly.  I If your blonde feels dry or coated, or loses shine, you may have mineral buildup from your hard water.

WHY DOES PURPLE SHAMPOO MAKE BLONDE DULL?

When used to frequently the pigments accumulate, creating a muddy or ashy grey film. If you use purple shampoo with hard water, it layers on top of existing mineral buildip, which creates a chemical overcrowding that results in lifeless, dull appearance.

Most purple shampoos are not nourishing and moisturizing as professional grade, so its best to get recommadation from your blonde specialist.