I did this the other week to clean a blocked filter and found it to be pretty straightforward.
Here's a link to the newtis.info.
https://www.newtis.info/tisv2/a/en/e89-z4-sdrive30i-roa/repair-manuals/61-general-vehicle-electrical-system/61-71-windscreen-washer-system/8J18GJ9T
If you don't/can't get access let me know and I'll upload screenshots.