Something the "Directed Energy Weapons" conspiracy theorists like to point out is how hard it is to find a photo of a porcelain toilet in the ruins of the houses. The only reason they can think of this is that the houses were destroyed by lasers or somesuch. But what actually happened to the toilets?
A big hit for this DEW theory is that if you look closely in the rubble there's lots of porcelain type stuff that survived just fine, like plates and bowls.
Another big clue here is that it's all broken. Understandable in the case of the dishes as they were once six feet up in the air in a cabinet. Toilets are on the floor, but the broken crockery reminds us that the house collapsed. The walls, those cabinets, the ceiling, the rafters and the roof dis not gently turn to ash and then float to the ground - they burnt until they lost structural support, then they fell.
And the floor is not the ground. Many houses in California, especially cheap houses, are built over a crawl space rather than a concrete slab. So when that fails the toilet will fall down, maybe crack, but certainly fall over, and be lost in the rubble. Here are some prefab homes on a crawl-space foundation. Notice the height of the floor above the ground (look at the steps)
After the fire only the steel foundation beams remain, albeit twisted, and the house is reduced to rubble in the crawl space.
No toilets are visible, but you really would not expect any.
But would a toilet even survive an intense fire? It seems possible that simply sitting in an 1100°C house fire for a few minutes would cause the toilet (and bathtubs and sinks) to shatter. But porcelain kilns are actually in the range 1,200°C to 1,400°C. Perhaps the issue would be the speed and unevenness of heating.