How often drain water heater?

[steamboatscott]

We use the RV about every 3-4 weeks for 3-7 night trips and have been keeping the water heater tank full of water during storage, only draining it at winterization and keeping it drained until springtime. Additionally, there are many trips where we won't use the water heater the entire trip. Is keeping water in the heater tank bad? Or should I be draining it after each trip to avoid letting the water sit stagnant? Maybe just flush it out more frequently than annually?

EDIT: the manufacturers manual states that a couple courts will remain in the water heater even after draining, so it seems like some stagnant water will always occur.

[flybouy]

A lot will depend on the quality of the water and the ambiant temps. Here in the DelMarVA area in July and August it can be in the 90's + in the daytime and not drop below 80 -85 at night. In those conditions I won't let it set over a week. In moderate temps 2 to 3 weeks. That's with decent weather.

It only takes a few min. And a little teflone tape so why put it off. Draining will also stop the sacrafical electrode from flaking away and settling in the bottom of the tank. When it gets "bad" you can get a sulfer smell from the hot water.