[Motor31]

Our rig had the anti siphon valve leak as well. It leaked twice, the first being because it never had the connections tightened at the factory. They were both loose and held on by just a couple threads. The second time it had just failed. They are fairly common at a well stocked RV supply house or dealer. I found the replacement on the shelf at a fair sized other brand dealer in Louisiana.

One thing to do is to make sure you do not have a water source hooked up to the black tank flush all of the time. If the water source valve is leaky and allows water to flow, even slowly, it can get up to the valve and a low pressure water flow seems more prone to leak than a full or moderate pressure flow when flushing. It also tends to fill up the black tank faster as well.