Start at the lowest point of the house. In most basements that is a corner, a floor drain, or the area under a main beam. In a crawlspace it is the soil farthest from the vents. Water that reaches the foundation from outside tends to find that spot first, so that is where you look.
Read the walls and the floor
Look for a pale line of mineral crust on block or poured concrete, a darker band at the base of the wall, or a white powder on the slab. Check the bottom of stored boxes and the lower edge of wood shelving. A musty smell that returns after a wet spell is worth writing down, along with the rain that caused it.
Read the outside grade
Stand outside and look at the ground next to the foundation. If the soil slopes toward the wall, or if a downspout ends a short distance from the house, water has a path toward the basement. Note where the gutters discharge and whether the downspout ends are extended away from the wall.
Check for a pump already in place
Look for a lidded basin set into the floor and a pipe leaving the house. Find the label on the pump or the motor housing and write down the year it was installed. If there is no label, ask whoever kept the house records. If the record is blank, plan from the first year you can confirm, not from a guess.
Ask what the pump is built to handle
Ask a licensed plumber or waterproofing contractor where the discharge ends, whether the pump has a battery or water-powered backup, whether there is an alarm for a high water level, and how the lid and power cord are protected. Ask for the answers in writing. A proposal that does not name a discharge route is missing a basic part of the job.
Decide what to log
Write down the low point, the signs you found, the outside grade notes, the pump label year, and the questions you asked. This is your planning file. It shows whether the house already has a plan or needs one, and it gives you a clear starting point for the next review.
Age is a planning input, not a verdict. An older pump may still be working well, and a newer pump may still need a backup. The electrical panel page on this site covers the service life of the panel that feeds the pump circuit, which is worth a look if the pump sits on an older panel.