Fitting it takes a minute
1. Unscrew the old head
By hand. Standard G1/2 thread, the same fitting used on common European shower hoses. No tools and no plumber.
2. Screw on Puremist
The filter element sits inside the handle, at the last point before the water reaches you. Keep your old head and put it back when you move out.
3. Swap the cartridge when it darkens
How often depends on your water. Replacement packs come in 12, 24 and 48 pieces, from €0.94 per filter.