I'm busy fixing burst lines from freeze damage in a foreclosure home I bought. I think when I'm done I can be reasonably certain that I fixed all the breaks, but then I thought it might be a good idea to install an in-line water flow meter just after the water softener/filter/etc. I won't be moving in to the house for at least a couple months, and with no one there using it I could easily see if there might be a slow leak that I maybe didn't find.

Has anyone done this in their home? If so, what brand/model did you use?

Just use a blue white.

It not in line, but they don't break easily like the in-line flowmeters do

Thanks... do you have a link to the model you're talking about?

I use a gate valve.  I shut off the water any time I am out of the house more than 2 days. 

If you're using city water do you have easy access to their meter?  If you have a well you can cut off the main water valve and well circuit then check the pressure gauge between site visits

To answer your question, not in your situation.  There is some friction loss but it may not be a problem for you.

It's a well, no public water.

I've heard of using the pressure gauge on the water tank. So, I just build it up to full pressure and shut off the power to the well, noting the reading on the dial?

You have to have a properly functioning main valve between the pressure tank and the house plumbing.  Turn the valve off for a week and then open it when you return.  If the PSI drops on the pressure gauge or you hear the water move through the valve when you open it look for a leak.

I should have said earlier, turn of the power source for the water heater.  

The best method is to do what ZW17 mentioned in his post.  I use air and a gauge similar to this and pump it up to a 100 PSI.  LINK  The gauge may drop 2 or 3PSI  because of temperature change but anything larger than that is probably a slow leak.

Do you have forced air heat or hot water system?

I have forced air heat.

I probably have at least another week or so of repairing lines, before I can fully test it. We're going to do a complete 2nd story bathroom remodel, which is good because there's some broken pipes up there as well.