We were out of town for aweek, and our dog was with our family members at their home, after we came back a week ago he isn't eating, only drinks a lot of water and begin pee at the house. He is 9.5 years old male soft coated wheaton terrier

A week of not eating and drinking excessive amounts of water?

He needs to see a Vet - this is beyond being angry with you for leaving him.

I agree with Judy, sometimes dogs can be angry with you for leaving but they will not starve themselves completely and they certainly don't start drinking water excessively.

There are many possibilities as to what it might be, the only way to know for sure is to get him to the vet.
It could be anything from diabetes to a urinary tract infection.

It doesn't change my advice any BUT (and the Vet always looks at me like I should be committed) my GSD drinks water like crazy and eats very little when she is shedding heavily. I have no idea why.

But I do take her to the Vet every 6 months so I know it's not a health concern.

The only thing I will add to the advice of a vet visit is to contact the people he was staying with and find out if anything happened during his stay. IF he could have eaten anything, been bit by anything, if there are other sick animals in the house, etc.