I am a builder. I installed my Bosch dishwasher.

Hello Gerry, There are two (2) ways to accomplish this. The easiest is to get some RV anti-freeze (enviromentally safe version) and put that into the bottom of the dishwasher as per the instructions. Then when you return in the Spring, just run an empty rinse cycle to purge the dishwasher of the anti-freeze solution.

The other method will require you to remove (pull out from under the cabinet) the dishwasher and (with power turned off!) disconnect the sump pump boot to drain the residual water out of the unit. In some models, there is a small drain plug that you can remove to drain the water out of the bottom sump (pump) section of the dishwasher.

Good that you thought of this, as many folks forget that leaving water in their appliances in freezing conditions can cause some major headaches from burst pipes, pumps, etc. if they aren't properly winterized for the freezing temperatures they'll get in an unheated building.

Hope you find this Very Helpful and best regards!

On Bosch dishwashers it is better to remove the inlet valve entirely (located at the bottom of the unit where the water intake line joins the dishwasher, usually requires a 7/8 wrench) and reinstalling it in the spring when you return. I've had to replace my inlet valve twice due inproper winterization proceedures even though I poured over a litre of RV anti-freeze and turned on the unit to distribute the anti-freeze it still was not enough.