DOG WONT PEE ON FAKE GRASS!

The drought here in West Texas is now affecting my dog. Yeah, us humans can't water our grass anymore and the city experts have told us we can only water our grass once a week. And, of course they're losing money so they have risen our water bills by 40 percent, but that's another gripe for another time.  Whats really interesting to me is the "fake grass" that has popped up in many a neighborhood here in west Texas. It's pretty much putting 'carpet' on your dead lawn. The other day while I was walking my dog 'bandit' I noticed that he won't pee on the fake lawn. We went down the blocks and I quickly noticed he would only raise a leg to fake grass be it green or dead. But, when we came upon the carpet 'fake grass' he would just keep walking by it. I'm thinking he's smart and knows he's not gonna waste his pee on fake stuff. Just an observation, but why then will he pee in my house with carpet inside and not on the outside fake stuff? Things to ponder while I walk my dog.