The water is circulating between the reflecting pool and the Tidal Basin. It was part of the 2009 upgrade to use that instead of using tap water.
They don’t typically circulate anything back to the tidal basin, the reflecting pool’s circulation system from the 2009 upgrades is a closed loop that filters the water and sends it back to the pool.
They have an option to top off the pool from the tidal basin to combat leaks/evaporative loss, but they don’t typically use that option during this time of the year (because the tidal basin is full of algae), and as far as I know they never use that method to completely refill it.
When it’s filled from empty, it’s treated water from DC Water.
They don’t typically circulate anything back to the tidal basin, the reflecting pool’s circulation system from the 2009 upgrades is a closed loop that filters the water and sends it back to the pool.
They have an option to top off the pool from the tidal basin to combat leaks/evaporative loss, but they don’t typically use that option during this time of the year (because the tidal basin is full of algae), and as far as I know they never use that method to completely refill it.
When it’s filled from empty, it’s treated water from DC Water.