The sounds that mean something's wrong
A healthy sump pump kicks on, runs briefly, and shuts off cleanly. Grinding or rattling usually means debris in the impeller or failing bearings. Rapid on-off cycling (short-cycling) often points to a stuck float switch, a failing check valve, or a pit that's undersized for how much water is actually coming in. None of these fix themselves, and all of them get worse under sustained heavy rain — exactly when you need the pump working.
Test it before you need it, not during a storm
Pour a few gallons of water into the sump pit and watch it respond. It should kick on promptly, move the water, and shut off cleanly. If it hesitates, runs but doesn't seem to move much water, or doesn't trigger at all, you've found a problem on a dry day instead of during flooding — which is the whole point of testing it now.
Battery backup isn't optional if you've had a power outage during a storm
A sump pump only works when it has power. If your area has ever lost power during heavy rain — which happens in Pierce County — a battery backup system keeps the pump running through the outage instead of leaving your crawlspace or basement unprotected at the exact moment it matters most.
Service life is finite, plan around it
Most sump pumps last somewhere in the 7 to 10 year range under normal use. If yours is older than that and you don't know the last time it was tested or serviced, that's worth checking before the wet season, not after you find water where you shouldn't.