What temperature is your water when you turn on the cold water tap? While you might expect it to come out cold, this is not the case for everyone. Finding out what causes this problem can be somewhat tricky, since there are many different possible reasons, and they might be hard to identify.

One possibility is that your pipes are uninsulated and run through a space that is very hot. This could be a crawlspace, a garage or something similar. If this is the case, you will find this problem will happen only in the summertime, and be worse at times when there is high heat outside.

It could also be a malfunction in the faucet itself, where it lets the hot water seep through. You could check if this is the case by noticing if the problem only happens at one particular faucet.

Yet another possibility is that something is wrong with your water heater, where hot water backs up into the cold water pipe. If you can identify the problem, it could save you some time and money if it is something that you can fix yourself.