OK, so here’s one more strange item you can add to the list of things you never even knew you might need. The fact, however, is that if your house is on a lot that’s not level, you probably need a Hose Bibb Vacuum Breaker like this one from Lasco.
Why? because of the siphon effect: when there's water in a hose that's above the point where it connects to the water supply, the water’s weight can force it back down the hose and into the water lines. That’s all well and good if you don't mind a bit of rubber or vinyl taste in your water, but if you don't want dirty water contaminating the water inside your home, install an anti-siphon device - vacuum breaker like this one - for an easy, inexpensive solution. Even if you don’t ordinarily run hoses uphill, you still need a vacuum breaker if you often fill water features or other large reservoirs like an above-ground pool.
Quality breakers are forged of brass, and simply fit on a hose bibb (faucet) with a female thread, just like garden hoses. They also have male threads where you attach a hose. The female end - the one that screws onto the faucet - has a set screw designed to break off – this keeps people from trying to take it off. Once it’s attached, the vacuum breaker will last for decades.
You can determine whether an anti-siphon device, or vacuum breaker, is working by trying to get water to run backward into the faucet: a working vacuum breaker just dumps water through the sides where it runs onto the ground. That’s much better than letting it run back into the house.
The Lasco Hose Bibb Vacuum Breaker’s design is pretty much as simple as it gets: it’s made of brass, has a breakaway set screw, and it’s essentially indestructible.