No pumping is required. On the down side, most such filtering devices are expensive and have a limited capacity. Filters are good for anywhere from 200 liters to thousands of gallons, depending on the filter size and mechanism. Some filters used fiberglass and activated charcoal. Others use impregnated resin or even ceramic elements.
Chemical additives are another, often less suitable option.
The water purification pills sold to hikers and campers have a limited shelf life, especially once the bottle has been opened. Captain Dave considers these good for the car's emergency kit, as long as they are frequently replaced. Pour-though filtering systems can be made in an emergency. Place several layers of cloth on the bottom of the bucket, this can be anything from denim to an old table cloth. This will be the main filtering element, so you should add at least half of the pail's depth.