We have had this Insta-hot&cold since we built our home 12 years ago. This is our third unit. The only downside is the hard water deposits collect over time and the whole top unit has to be replaced. The bottom heater we replaced once due to a leak. The unit comes with the tool you need, but getting under your sink and up behind it is a pain. It is a DIY for those that know how to use a tool, but not for everyone. Took us 20 minutes to swap and 10 minutes to move the under sink contents. It may be done solo, but much easier with two.