What type of drain below hot water heater

What type of drain should be used below a hot water heater? A standard p-trap below the floor would have a tendency to evaporate out allowing sewer gasses in so what type is usually used?

 

If you want to do it correctly, then a p-trap is mandatory, but you also need to use a trap primer to keep that p-trap primed.

Some codes will actually allow the homeowner to forgo the use of a trap primer so long as they manually fill the trap from time to time, but that is not exactly a reliable method since the homeowner will quickly forget all about it.

 

Fill the trap with mineral oil. It won't evaporate out like the water will.

 

I don't have a floor drain in my basement for my water heater or anything else. The sewer pipe outlet is a few feet higher than the basement floor level, so it impossible to use one in my basement anyhow!