1. Water heater failure
Tanks corrode from the inside and fail at the seam, releasing 40 to 80 gallons and then continuing to refill. Attic installations — standard across much of Texas — put that directly above finished living space. Early signs: rust at the fittings, popping sounds, moisture in the pan.
2. Washing machine hose burst
Rubber hoses fail at the crimp under constant pressure, typically after five to eight years. They fail while you are out, which is why these losses average so much larger than their volume suggests. Braided stainless replacements cost about $20.
3. HVAC condensate overflow
Biofilm blocks the primary drain, water backs into the secondary pan, and the pan either overflows or has already rusted through. Extremely common in Houston attics every summer. Prevented entirely by an annual line clearing and a working float switch.
4. Slab leak
Under-slab copper abrades against concrete as expansive clay soil moves seasonally. Water surfaces through the slab into flooring and wall bases, often far from the actual break. Warm floor spots and running-water sounds are the classic indicators.
5. Toilet supply line and wax ring failure
Plastic supply nuts crack and wax rings fail silently, leaking under the flooring every flush. A toilet that rocks slightly is telling you the seal is compromised. Ceiling stains below a bathroom are the second-stage symptom.
6. Roof and flashing leaks
Vent boot rubber degrades in Texas sun within ten to fifteen years. Water enters at the penetration, travels along rafters, and appears on a ceiling well away from the entry point. Attic inspection after heavy rain finds these long before the ceiling does.
7. Sewer line backup
Roots enter clay and cast iron laterals at the joints, then grease and debris accumulate on the intrusion until the line closes. Multiple slow drains and gurgling fixtures are the warning; a Category 3 backup is the event.
8. Shower pan and grout failure
Pan liners fail at the corners and grout develops hairline cracks. Water bypasses the waterproofing into the subfloor, and because it only happens during use, the damage accumulates for years before appearing below.
9. Wind-driven rain intrusion
Failed sealant at windows, doors and wall penetrations lets water in only under specific wind and rain conditions, which makes it maddening to diagnose. Systematic water testing reproduces the conditions and finds the actual entry point.