It's very location-specific, and he didn't eliminate in the house for 7 months, just these times in the basement.

Is there any chance at all that another animial urinated on the floor in the past? I know you have new carpet but if another animial went there it could be in the subfloor.

Maybe it's because little boys like to mark. When I got my dog, he would pee on other people's ankles.

I agree with ell above. You have to keep him with you. It's inconvenient but worth it. He needs to go out a lot.

My dog urinated on new carpet we had installed but only once. The carpet had to be pulled up due to color errors by the manufacturer and that's when we saw my dog had peed on it. The installer said it wasn't unusual and that dogs often peed on new carpet. Must be something about the odor.

I assume your guy gets lots of exercise and is able to let you know when he needs to go out. I suggest spending more time with him in the basement and he should learn it's territory for everyone.

Peeing can often be due to marking but suddenly pooping in the house is usually due to diet or a more active bowl, and no access to outside......IMO.

Your dog has WAY too much freedom to be doing this.

first thing i'd do is get him checked for a UTI. if that turns out to be negative, then it's a behavioral issue.

anntzoo, I think your analysis may be right. Both places have new carpet. He has NEVER eliminated in our house in the past 7 months. The two times he went at the lake were times he was inside and we were outside. He is normally kenneled and not left alone. Thanks for the input.

Training your pet to do its excretion in a specific place or outdoor is only solution but difficult part is it can't be achieved in short period.
But you can find a commercial repellents and also you can use White Vinegar, Lemon Juice, Rubbing Alcohol as repellent agents. Repellents acts effectively to keep your pet away from carpet. And keep training your pet as you might not want to use repellent forever. When your pet starts to follow the rules stop the use of repellent.

Let me know if this is helpful.