In my school I have had an issue with the toilet supply water being very warm. As this is feed from the cold supply and there is no mixing valve that we can find on the line. How is the water becoming very warm if not crossed with a hot water supply line?

I have seen plumbers plumb in hot water to the toilet because they lost track of which was which, 2 copper or 2 CPVC pipes look the same.
We have Cap Rock down here, and when we got the house the water line was on top of the ground, water was warm or hot, 2 week of trenching and chipping got it under ground, now the water is colder.

Hi Amiller

I am guessing that this is something that has just popped up and did not exist prior to this, yes? If that is the case, then there must be a single handle faucet/valve and/or mixing valve somewhere on the cold water line close by...

Do the sinks in this bathroom have single handle faucets?

How about a shower valve... anywhere near this toilet?

How about a washing machine... is there a washing machine or a mop sink faucet near by?

How about a recirculating hot water line (may connect into the water heater cold water feed via a check valve that has failed, etc.)?

Keep looking...has to something that is crossed or failed... ;)

Let us know more on this, OK?

Mark