Do I have a Leak?

I recently installed a booster pump between my well and two buildings, my house and a garage/apartment. I've noticed that the pressure drops ever so slowly even when the water is turned off everywhere. If I turn the valve off to the house it stops, so, If i need to look for a leak I assume it would be in the house. Problem is, i can't find one. I can't find damage anywhere. Questions are, is this normal? Is there an appliance that would cause this? Is there some kind of test i can perform to find the leak?

I've lived here for 20 years and do have copper pipe in the slab.

Ray,

You did not say how close the valve is to the house, or even if it is in the house. However, the leak, as you have concluded, is somewhere after the valve. If it is away from the house don't forget to give the section feeding the house some consideration

If you have no visible faucet leaks, try turning off your toilets. Other considerations would be the T&P valve on the water heater, dishwasher (unlikely or you would probably have had water on the floor), fill valve to your heating system (if you have hotwater heat, unlikely), humidifier........ under slab.

Process of elimination.

If you have well water, it may be hard on the copper. It is in our part of the country.

Paul

The valve is in the garage and the water probably travels less than 30 ft. before getting to the house. I have checked the toilets to see that they are not leaking, but have not turned them off. It's not the hot water heater and i don't have hotwater heat.

Hopefully, i will see a muddy spot show up in the ground between the garage and the house. I did look, but this is a very small leak. It drops one PSI in about two minutes and then slows as the pressure drops. The PSI in the house was always low 50s or less which is why i added the booster pump. I'm hoping the booster pump which tops out a 75 PSI didn't cause a leak at a weak connection in the slab.

I just need to take some time, turn everything off and work from there.