purple/pink tinted domestic water...why?

[gravel]

I notice in an old school building repurposed for office use, the bathroom fixtures having water within them of light purple-ish color...more noticeable if standing over weekend.
Water source is public water. Maybe the color is a result of lead piping leaching?? Or high residual chlorination?? just guessing of it, but was curious of real reasoning of the coloring. Anyone know?

 

[ashtree]

Copper plumbing and corrosive water will give a blue or blue greenish tinge to water especially after sitting for a while. In my experience though i would't have said it was purplish.
Corrosive water is often lower pH , low in alkalinity and hardness and low conductivity. Supplies that are dominated by snow melt as a source sometimes have this problem seasonally.Supplies with a high percentage of RO permeate, that is not adequately stabilised can suffer this problem but there are other causes as well.



Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[bimr]

Green or blue water staining are names given to a general corrosive attack that on rare occasions occurs in buildings that have been plumbed in copper. Classic cuprosolvency typically occurs in water that is relatively soft, low in pH, and high in dissolved gases. It generally is characterized by elevated levels of dissolved copper in the water. However it does not usually result in high levels of particulate copper, or suspended copper corrosion products in the water.

Manganese stains are sometimes described as purple-black.

Perhaps the light source makes it difficult to determine the true color.

 

[btrueblood]

from

https://en.wikipedia.org/wiki/Potassium_permanganate#Water_treatment:

Water treatment
Potassium permanganate is used extensively in the water treatment industry. It is used as a regeneration chemical to remove iron and hydrogen sulfide (rotten egg smell) from well water via a "Manganese Greensand" Filter. "Pot-Perm" is also obtainable at pool supply stores and is used additionally to treat waste water. Historically it was used to disinfect drinking water[8][9] and can turn the water pink.[10] It currently finds application in the control of nuisance organisms such as zebra mussels in fresh water collection and treatment systems.[11]

 

[ashtree]

Potassium permanganate is used in the water treatment industry and is pink or purple in color. However it will not/should not be dosed in a manner that causes the water around the city to be pink. If it was being dosed in such a manner than the pink color will be throughout the whole system not just in an isolated part so is unlikely to be the cause of the problem unless it is somehow finding its way into the system at a local level.

Permanganate is typically dosed in the raw water coming into the water plant or ahead of the filters. The pink color dissipates as it oxidizes, organics , manganese and iron.



Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[utilengr]

If it's in the water is may be something different but going by your comment that, "more noticeable if standing over weekend", and if it is primarily on the fixtures or in the sinks/showers, it sounds like Serratia marcescens. This is a common bacteria that is the color you describe. It is more prolific in warmer/humid environments.