I just purchased a 10 year old house and found the sump pump piped into the sewer line. Are there any major issues with this?

Yes, it may be againist code. You need to check with the city building department to see how their code reads. Many towns require foundation sump pumps to be piped outside to day light.

Bob may turn you in but I won't.

What was that address.

In some older homes with drainage issues, there is times when the pumps can cuase water to back up in the lines, but that is a dain blockage issue.

Also is there a one way valve on the outlet to stop sewer water from going back into the sump

My town allows sump pumps to tie into city house sewer, but the town twenty miles away does not. So, As Bob said, its best to check with the local authoritys.

I just purchased a 10 year old house and found the sump pump piped into the sewer line. Are there any major issues with this?

If your pump doesn't have a running trap, (see image) installed then you have a direct open connection between your home and the city sewer system allowing sewer gas to enter your home. In my area it's against the law to discharge ANYTHING in the sewer except sewage and gray water. The reason being the sewage plant has to treat all water as sewage and process it. It runs the cost of operation sky high. Good luck, Tom