Allowing the water to sit motionless in the pipes allows the bacteria-killing chlorines to dissipate, and that's exactly what investigators said happened in Louisiana.
"We designed our system where it's looped, and that means there are no long, dead-end lines. I'm assuming in these small rural areas that is the problem they have, is they have long lines, with not a lot of customers using it, so the water doesn't get turned over often enough,” said Roy Foster with the City of Tulsa.
In fact, chlorine tests in the Louisiana tap water revealed very low levels of disinfectants, less than 0.5 parts per million, meaning those pipes should have been flushed regularly to keep the water safe.
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The results show Tulsa's water had four times the amount of disinfectants in its water than the water in Louisiana, an average of 2 parts per million, meeting state regulations.
I went to the link and read the info before responding to your post.
It looks like the treatment is probably the same. Handling the water after the treatment is (hopefully) better in Tulsa.