Common problem.

Look at it this way, you are doing a slow coolant flush by continually adding water to the system.

Be careful taking the hoses off the old reservoir. The connectors may be brittle due to the age of the system.

__________________
Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual