jones wrote:

Is there an easier way for him to check for leaks?

It really is about money. Plumbers do not come cheap and competent
plumbers can be rare.

Len's comments are spot on about looking for wet ground, etc. If you can
find the leak yourselves, you can save a lot of the plumbers time and
your money.

The alternative is replacement. If you think about it, if you have to
dig up extensive lines of piping, then you have done the hard work and
might as well replace it with new stuff.