Greg is correct on removal of services not being allowed.
To add to it:
In Waterloo the water is very `hard` so it is strongly
recommend. This will vary from city to city so it will depend where your rental
is.
The issue with not having one if you have hard water is mineral
build up on pipes and water items that can cause failure faster (ie you might
need to replace taps, plumbing lines, etc. early), it can leave streaking /
marks on sinks and faucets, and feel like its hard to get clean (soap /
detergent doesn`t work as well.
The issue with having one is cost of initial installation, cost
of maintenance, and cost and time of installing water softener salt on an
ongoing basis. You also need to ensure its not going to anywhere there is
drinking water. I also have heard concerns about absorbing extra salt through
skin when bathing but do not how significant this is.
From a property management stand point if you are currently
providing one, you are obligated as a service to your tenants to continue to
provide one. You should get them signed off in writing that they agree and want
you to not have a working water softener.