Here’s a question from a reader of RVtravel.com about boondocking.
Hi Bob,
I have assumed that if I turn off park water and turn on my water pump and it is quiet, that is a good indication of no water leaks. Anything wrong with my theory? —Tom
Hi Tom,
You’re mostly right. If your plumbing system has no leaks then it will maintain pressure in the system until you turn on a faucet or flush a toilet. This depletes the pressure in the system and the water pump will turn on and run as long as the water is running. When the water flow stops, the system builds up the pressure again and at a preset point the water pump will turn off and remain off (and quiet) until the next usage. 
However, if you have a tiny, almost imperceptible leak, that may take hours before it allows the pressure to drop enough for the water pump to turn on, and you may not notice it. You might not be in your RV, or be asleep or watching TV at the time the pump turns on. And in this case, the pump doesn’t need to stay on very long to get the pressure up in the system so you may not catch it.
But wherever the leak is, no matter how small, it will keep the leak area damp and encourage rot and mold, so it is important to periodically check those hidden places just to make sure you are leak-free. Use a strong flashlight to search those hidden places, as well as feeling for dampness. Once identified, fix immediately and use a portable heater to dry out the area.
Read more about boondocking at my BoondockBob’s Blog.
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Do you have a question for Bob? Email him at bob.rvtravel (at) gmail.com .
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Hmmm, you’ve stuck a nerve. But not what your thinking, its about using a strong flashlight to find the leak! I’ve adopted the CSI method of using a very bright pin-point flash light for whenever I’m looking for just about anything. Just give it a try & you’ll see your eye will follow the light beam & you have a better chance of finding what your looking for. When I saw those iinvestigator’s using their flash lights during the day I used to laugh, now I know why!
Dave
One more item that can confound the issue: an accumulator. I added one to my RV to quiet down the pump (and reduce it’s spike loading). The accumulator holds about 4 ounces of water, so it must be depleted a bit before the pump kicks on.
That said, all the leaks I’ve had — even the small ones — have triggered the pump enough for me to notice.