Milk instead of water for sourdough? I have a nice, healthy Type 110 wheat-based sourdough starter that I use to make bread and pancakes.

I've recently discovered that it may be possible to feed the starter with milk instead of water. Is this true? I'm a bit paranoid that rotting milk will introduce unwanted bugs that rotting flour won't. How would it affect my starter? Or should I just stick to water in the starter, but add milk to the bread, instead?
Adding milk works because milk is mostly water. It might even work better, as it also contains sugar (lactose) which will be eaten by your starter's yeasts and bacteria.

But it also contains other stuff, such as fats. And fats, after some time, get rancid. You probably won't want that taste in bread or pancakes. I would stick to water (which quite probably you'll find cheaper than milk).

Don't worry about rotten milk: your starter is already rotten. And it's a hostile environment for most microbes. It's very very improbable new microbes would survive there. But if they do, they'll be quite similar to the already existing ones.