Why leaks matter
Water escaping from supply or drain lines can create localized moisture differences in soil. In moisture-sensitive clay, that change may affect soil volume and support conditions around part of a foundation.
Foundation movement can affect plumbing too
The relationship can run both ways. Movement in a slab or surrounding structure can place stress on rigid plumbing, joints, or penetrations. A plumbing issue should not automatically be assumed to be the original cause.
When testing is useful
Leak testing may be worth discussing when there are unexplained moisture clues, unusually high water bills, plumbing symptoms, significant slab movement, or a repair plan that could affect buried lines.