This is our water softener-filter installed.  And yes, the second set of screw holes in the wall provide evidence of us getting it in the wrong place on the first attempt.  Not happy.  It's a clever unit offering the correct hydrogen ion replacement method of softening (not the vastly cheaper sodium ion replacement softening which is now illegal for water that is intended for drinking) and undertaking acid-base buffering to ensure the water is not 'over-softened' and result in corrosion in your espresso machine.

You will see we have added in a flow meter which connects to a digital reader to log the number of litres that have been filtered, with an audible alarm sounding when you have exhausted the filter, which won't take too long with the small capacity of this filter combined with our rock hard water with a total hardness (TH) reading on the wrong side of 450ppm.  For this reason we have elected to sell the Claris range of filters which are available in a range of capacities, but the bottom line is they filter a lot more water for a lot less expense.  The Claris doesn't offer acid-base buffering, instead you have to manually set a bypass valve to get the correct proportion of softened and unsoftened water, but the cost saving more than outweighs this inconvenience.

We would recommend the digital flow meter though as it ensures you only change your filter when you need to, not on an arbitrary time-based interval.  In a hard water area, like London, this additional outlay has a short payback period.