| A gas smell anywhere in the house | A gas leak; not a water problem yet | Leave, then 911 and the gas utility (numbers below) | Do not go back in until you are told it is safe (CDC) | None: the utility comes first |
| Water touching outlets, cords, the panel or plugged-in appliances | Any source; the danger is the power | An electrician, if the breaker can only be reached through water (CDC) | An electrician checks the system before the power goes back on (CDC) | Electrical |
| Water spraying or running from a pipe, fitting or supply line | Plumbing (clean water) | Shut the main water valve, then a licensed plumber | Restoration if water is standing or materials are soaked | Plumbing |
| A puddle around the base of the water heater | The tank, a fitting or the relief valve | A licensed plumber | Restoration if carpet or drywall got wet | Water heater replacement |
| Water at the washer, utility sink or dishwasher line | A hose, drain or appliance (often gray water) | Shut the appliance valve, then a plumber | Restoration for wet materials; appliance repair for the machine | Plumbing |
| A burst pipe after a cold snap | A frozen pipe | Shut the main valve, then a plumber | Restoration; call the insurer the same day | Plumbing |
| Sewage or dark, smelly water rising from a floor drain, toilet or tub | A sewer or drain backup (Category 3) | Stop running water; call the town's sewer utility to ask whether the public main is backed up, then a plumber or sewer service | Restoration that handles Category 3 water | Sewer line repair or drain cleaning |
| The sump pit is full or the pump is not running | A failed pump, a power cut or a stuck float | A plumber or waterproofing contractor for the pump | Restoration if the floor is covered; check your sump overflow endorsement | Plumbing |
| Water along the wall-to-floor joint or through wall cracks after rain or snowmelt | Groundwater or surface water outside | Restoration first if water is standing | A foundation or waterproofing contractor once dry; a structural engineer if the foundation itself is the issue (Angi) | Foundation repair |
| Water coming in under a basement window or a filling window well | Roof and gutter runoff or grading | Restoration if water is standing | Gutters, downspouts and grading so rain drains away from the house (CDC) | Gutter repair |
| Inches of standing water, or wet carpet, drywall or insulation, whatever the source | Any source | A water damage restoration company the same day | The trade that fixes the source, from the rows above | Water damage (this page's form) |
| Damp walls or sweating pipes with no puddle and no running water | Often condensation; EPA says condensation can be a sign of high humidity | Nobody urgently: dry the air and watch it | Mold remediation if you smell must or see growth | Mold remediation |