Strainer. A screen installed in the flow that allows water to pass, but not larger items, which fall to the bottom or are held in a basket for later removal. Strainers come is several different styles. A plate strainer, a perforated plate through which water flows, is the simplest. The plate may be corrugated to increase surface area. A basket strainer is shaped like a basket and usually installed in a vertical cylinder. This type of strainer, which captures debris in a basket, is easier to clean. It offers more straining surface area than a plate strainer, improving flow rates and decreasing pressure loss.