CISTERNS collected cistern is a structure that captures and stores roof runoff. The collected in a water can be used for landscape and some interior uses, such cistern Aas and washing machines. It is possible to use a cistern system for can be household drinking water if it has proper filtration, inspection and permitting. reused Cisterns are constructed of durable material, such as concrete, plastic, polyethyl- in the ene, or metal. They are larger and usually more permanent than barrels, landscape ranging in size from 100 gallons to 10,000 gallons. They can be placed above- ground, underground or on a rooftop.

A roof washer or filter removes contaminants and debris before the runoff enters the cistern. A pipe from the cistern conveys the stored water, either by gravity or pump, to the designated interior or exterior use. In some instances, an overflow system conveys excess runoff to a destination location. At sites with soils that drain , the overflow can be conveyed to onsite landscaped areas or into perforated underground pipes if permitting requirements are met.

Benefits washout from cleaning can be disposed of Using a cistern to store and reuse rainwater onsite to vegetated areas if disinfecting reduces or eliminates stormwater runoff from agents are adequately diluted so they do not the site. It conserves potable water and harm plants. Schedule cleaning during dry reduces water charges with an installed weather. A cistern and its components have a meter. Cisterns are available from many lifespan of 20 to 50 years, depending on sources, and are relatively easy and inexpen- location and material. sive to install and maintain, especially if they are above ground. Rainwater can be used for Cost potable applications if the water is treated Costs for a cistern, not including installation, and meets state and federal safe drinking range from about $250 for a 200-gallon cis- water standards, and the system meets per- tern to $5,000 for a 10,000-gallon cistern. mitting requirements. Safety and Siting Requirements Maintenance • Only collect roof water for reuse. Do not Inspect the cistern periodically to ensure reuse water from parking or pedestrian debris does not clog the system. Check for areas, surface water runoff, or bodies of leaks at connection points. Clean the cistern standing water. interior annually with a brush and vinegar or • With the proper permitting, underground other non-toxic cleaner that will not degrade cisterns in areas with soils that drain well water quality or harm the cistern. The may be approved to overflow into under- ground perforated pipes. • In areas where soils do not drain well, • Rooftop cisterns require a building permit overflow to a city system is required. for structural review and approval by BDS. • Refer to Portland’s Stormwater • Underground tanks require a grading and Management Manual for detailed sizing, erosion control permit. placement, and design information. Examples Permits DaVinci Middle School (aboveground) • Installing a cistern requires a plumbing 2508 NE Everett Street permit from the City’s Bureau of Development Services (BDS) because instal- Portland State University-Stephen Epler Hall lation usually involves altering or adding (underground) plumbing components. SW 12th and Montgomery • Any pumps or other electrical controls Oregon Natural Resources Council (ONRC) require an electrical permit from BDS. (underground) • Any cistern footings, foundations, enclo- 5825 N Greeley Avenue sures, and roof structures require a build- ing permit from BDS.

aboveground underground

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