Columbia River
The Columbia drains an area of about . Its drainage basin covers nearly all of Idaho, large portions of British Columbia, Oregon, and Washington, ultimately all of Montana west of the Continental Divide, and small portions of Wyoming, Utah, and Nevada; the total area is similar to the size of France. Roughly of the river's length and 85 percent of its drainage basin are in the US. The Columbia is the twelfth-longest river and has the sixth-largest drainage basin in the United States. In Canada, where the Columbia flows for and drains , the river ranks 23rd in length, and the Canadian part of its basin ranks 13th in size among Canadian basins. 
The Columbia shares its name with nearby places, such as British Columbia, as well as with landforms and bodies of water.
Greywater
Although Canada is a water-rich country, the center of the country freezes in the winter and droughts happen some summers. There are locations where watering outdoors is restricted in the dry season, some water must be transported from an outside source, or on-site costs are high. At present, the standards for greywater reuse are not strict compared with other countries. The National Plumbing Code, which is adopted in whole or in part by the provinces, indicates that non-potable water systems should only be used to supply toilets and underground irrigation systems, collecting rainwater with roof gutters is included as a form of greywater. Health Canada has published a guideline to use greywater for toilet flushing and British Columbia's building code includes subsurface irrigation with greywater. In Alberta "wastewater from any source cannot be used inside buildings" Saskatchewan also treats greywater as sewage.