Water heater

If you leave the water in the tank you are adding about 10 kg to your vans weight and all that water sloshing around as you travel might not do your heater any good.  

There is also the potential of the water freezing and splitting the pipes causing a leak.  

My advice would be to drain down every time you travel. 

I drain down as don't like the thought of washing or washing up with water that has been left sitting even for a week. I'm no expert but I'm sure there would even be a risk of legionaires although probably very low not something I'm going risk.

I always drain down, even in summer. Why carry extra weight?

Thanks for your answers. I was more concerned about legionaires than the extra weight.

Drain down if not in use and freezing conditions are expected! 

The main need to drain down is to avoid the water freezing. If it’s not going to freeze, you could leave it in without concern, other than the extra 10kg that you’re carrying. Motorhomers rarely drain down (or, at least, I rarely do).

If you are using the van regularly and are not concerned about the weight then there is no need to drain down unless cold weather is expected. As long as your water is hot enough the risk of legionnaires is very low. We use our van most weeks and never drain down except during winter months when there is a risk of freezing.

We always drain down or hot water heater after every trip. We do it as we pack things away before travelling home. It's a simple matter of unscrewing two taps and it's done.

Same as AndyNY.

I've never had a problem with extra weight or instability. In winter I always drain down. Open the drain plug when leaving site and close it when I get home. That way I get rid of all water in the pipes..

I drain down whenever leaving a site and recharge it at the next, even though we caravan all year round.