This small, reliable sump pump has a pressure-activated internal switch and can move more than 2,500 gallons of water per hour. The filter enclosure it fits in was cobbled together with some window screen attached to a loop of Romex.
Riveting a plastic flap between the vac's hose inlet and the filter helps keep the filter dry and free from muck during wet cleanup. For dry vacuuming, the flap protects the paper filter from incoming jagged debris.
A vac muffler is a great $12 investment. It makes a notable reduction in volume and mellows out the shrill pitch of a vac. No other tool you own is on as many hours as your vac, so making it more pleasant to be around is worthwhile.