Add the following to your pre-inspection questions if the house is unoccupied and it is winter in areas with temperatures below 30 degrees: BEFORE the inspection tell client it would be an incomplete inspection if the house was winterized and you couldn’t inspect everything. Tell them it is imperative they get seller to ensure that everything has been turned on for the inspection, to include water, sewage, gas, heat, electric, etc. And as others have said, note the condition when you walk in with pictures, and then note the condition with pictures after the inspection of everything as you depart, so you can prove how you left it. If things are not turned on at the supply, don’t just assume it will be ok to turn them on for the inspection and then turn them off later. Not a good idea…if pipes are already cracked and burst…but not visible…you could be adding to or causing all kinds of damage that may or may not be immediately visible. So avoid turning supply lines on if they are off. And drain lines might have RV anti-freeze in them so if you pour water down the drains you’ll flush that anti-freeze away, so it would need to be replaced. Just be careful with those types of inspections, risk of you creating or causing damage is high if you are not careful about what you do and how you do it.