My wife and I just moved in to a brand new house and have started to notice that the water in the toilets is an orange color, and is starting to leave stains in the bowl. After looking online briefly, I have seen the suggestion that perhaps there is rust in the plumbing. I know that all of the plumbing in our house consists of what appears to be plastic piping... is there any other explanation? What steps should be taken to fix the problem?
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..
This is clearly not rust in this case, nor is it probably sediment, but bacteria. They are probably living on something in the water, and often that is iron.
Does your hot water also smell a bit, with a bit of rotten egg smell?
If so, then you probably have either iron or manganese in your water supply to the house. Bacteria live in your hot water tank, and your toilet tank.
Get rid of the iron to get rid of the things it causes. To do that, you will need to remove it somehow, and there are several treatments available once you figure out how much iron is there. Start with a home test kit, which you can buy inexpensively from your local home store.
If you have potassium thiocyanate you can test for ferric (Iron-3 aka rust) by dropping a few drops into the toilet. If it's rust, it will turn blood red. Ferric isn't terribly damaging as far as health-effects go, but it is definitely gross. I'm testing one of the drinking fountains at my school right now with the AP Chem class. Based on my research, it could also be Chromate or Pervanadyl, which could cause potential health risks. Good Luck.
the stain is coming from the water supply. county water would not tell me what they use but it started at my house three years after i had moved in. at that time the county change chemical vendor and the orange stain appeared. it has been there now for 12 years. it easily wipes away but you must wipe it.
My water ran orange or red like our dirt after the fire department tapped the water lines to fight a house fire in our neighborhood. I called the water department and that's the first thing they checked. They told me that it would run clear after the lines were flushed and recapped. What color is the dirt in your region?