Hey plumbers out there, I got a situation, I figured I'd post it here, because it feels more like a mystery than a problem and I wanted to see what professionals thought, or if they've seen something like this. Details in body.

First off let me be clear, I'm not a plumber. I used to set up mobile homes so I am familiar but far from the trade, so apologies if I get terms wrong or it's hard to understand this. Also given the mystery of this issue, it might be hard to understand. So just take me at my word, and I may get terms mixed up but I won't refer to the term differently after applying it. Here it goes.

There's no pictures. The house is dry, everything is fine, and there no leaks. As far as an inspection of the house/property has to say. No leaks or swells in the underbelly of the mobile home, no issues with the water heater, no heavy flow into the sewer system. As far as an inspection can tell the house appears fine.

The issue is that the house has shown $1000 of extra water flowing to the house over the last month. So we checked all the valves to see where it's happening. We had the city out there, the park manager, my dad, myself, and a third party inspector. The system has 4 valves going from the City to the mobile homes water. I may be defining these wrong but here they are as far as I know them, the city valve, the park valve, the street valve, and the gate valve. The city valve is where the meter we're using is at and where the city connects to the park, the park valve was not disturbed, the street valve is where the mobile home lot connects to the park, and the gate valve is directly on the side of the mobile home connected to the street.

When the all valves were ON (water flowing) water was indeed flowing like crazy, worthy of $1000 month difference. We then turned the street valve OFF, and the gate valve OFF. Water flow went back to expected flow rate. We then turned the street valve ON and left the gate valve OFF. Flow remained within expected rates. We then turned the gate valve ON. The meter started spinning like crazy, back to the signs that there was a massive leak happening.

So that's where the mystery is. The city shows that a huge leak is happening, it seems like it's happening after that gate valve, but there are no signs under the house. No weird noises, no standing water, the plastic holding the insulation under the floor isn't holding water, there are no wet spots anywhere in the house. Everything seems 100% normal.

Has anyone seen something like this? Even better, anyone got any good stories about something that started like this?