Why is the water in my toilets orange?
If the house was vacant for a long period of time, there might be build up in the pipes. Try running a number of facuets for a while and flush the toilet over and over.  Assuming your incoming water isn't orange, it should go away after you flush out the pipes.

Also open the tank and have a look in there - maybe there is a component of the toilet that is rusting, or maybe there is some type of cleaning tablet present (usually they are blue but you never know).

EDIT: You mentioned in your comment that there is orange sediment on the bottom of the tank.  I can't really guess at what this is (maybe orange soil as someone in the comments suggested), but I would suggest that you turn off the water to the toilet, flush it to empty the tank, and then using a sponge, scrub it off, or at least disturb it enough that it will wash away when the tank refills.  Turn the water back on and flush it away.

If it comes back after some time then you'd need to investigate further..