That musty smell you can't place
You noticed it a few weeks back. A faint mustiness near the hallway bathroom, or maybe under the kitchen sink cabinet. Nothing dripping, nothing pooling on the floor, so you figured it was nothing and moved on. In a lot of Nixa homes, that's exactly how a slow leak announces itself, not with a puddle but with a smell, a slight softness in a baseboard, or a utility bill that crept up a little without explanation.
These are the leaks that never reach the floor. Water finds its way into a wall cavity, under a subfloor, or behind a tub surround, and it just sits there, evaporating slowly enough that you never see the evidence pool anywhere obvious. Around here, with our mix of older ranch homes off Highway 14 and newer builds out toward the McCracken Road corridor, both plumbing types have their own version of this problem.
Why our clay soil and weather make this worse
Nixa sits on soil with a lot of clay content, and clay swells when it's wet and shrinks hard when it dries out. Through a normal year here, that means the ground under your slab or around your foundation is constantly shifting a little. That movement stresses supply lines and drain connections in ways that homes on sandier or rockier soil don't deal with as much. A joint that was fine in March can develop a hairline gap by August after a dry stretch, or after the freeze-thaw cycles we get most winters.
Southwest Missouri winters aren't brutal, but we get enough hard freezes, followed by 50-degree days, to put real stress on pipes, especially in crawlspaces and unheated garages, which are common in homes built before the 2000s in this area. A pipe doesn't have to burst outright to start a slow leak. Sometimes a freeze just cracks a fitting enough that it weeps rather than sprays.
More on this from The Quiet Leaks That Never Reach The Floor.
What you can actually check yourself
Start with your water meter. Turn off every faucet and appliance in the house, note the meter reading, wait an hour without using any water, and check it again. If it's moved, you've got a leak somewhere, even if you can't see it yet.
Walk your crawlspace if you have one, especially after a wet spring. Look for damp insulation, dark staining on floor joists, or a sour smell that's stronger there than elsewhere in the house. Under sinks, pull everything out of the cabinet once in a while and feel the shutoff valves and supply lines with your hand. A little bit of dampness or a chalky white mineral buildup around a fitting is often the first physical sign, well before you'd ever see water on the cabinet floor.
Check your water heater's drain valve and the fittings on top of the tank. These units tend to last a good while in our water, which runs moderately hard, but connections loosen slightly with age and vibration, and a slow weep there can run for months into a drain pan that eventually overflows unnoticed.
Signs that mean it's past a DIY fix
If drywall feels soft or spongy when you press on it, or if you see a stain that keeps reappearing after you paint over it, the water has already been active long enough to do real damage. Same goes for a wood floor that's started to cup or a laminate that's swelling at the seams even though the surface has never gotten visibly wet. At that point the leak has usually been running for a while, and cutting into a wall or floor to trace it is not a weekend project most people want to take on themselves.
A meter that keeps ticking after you've shut off every fixture in the house is another one. That tells you the leak is on the supply side, likely underground or inside a wall, and pinpointing it without the right equipment usually means guessing with a hammer, which causes more damage than it fixes.
Why waiting costs more here than elsewhere might suggest
Because of the clay soil, a slow leak under a slab in Nixa doesn't just sit still, it can wash out small pockets of soil underneath the foundation over time. What starts as a plumbing problem can slowly turn into a foundation problem if it runs long enough, and that shift happens quicker here than it would on more stable ground. The humidity we get through a typical Ozarks summer also means any hidden moisture has a much easier time turning into mold once it's had a few weeks to sit undisturbed in a wall cavity or crawlspace.
None of this means panicking over every musty smell. Plenty of them are just seasonal humidity and nothing more. But if the smell persists past a week or two, if a utility bill jumps without an obvious reason, or if the meter test shows movement, it's worth getting someone with a leak detection camera or acoustic equipment to actually find the source before it turns into a bigger repair than the plumbing itself.