Draining Down for Winter

We all drain down our hot and cold water systems for winter or should do at least. But what about the windscreen washer reservoir. With the forecasted prolonged very cold spell ahead of us perhaps it would be a good idea to empty that too unless it's filled with a winter solution.
€2.94 at Aldi this week

Just add a few hundred Mls of Meths 20% will give you protection down to -9°C which is plenty for Ireland. 30% will give you -15°C