About Water Conservation & Cisterns

Cisterns

A cistern is a vessel used to hold water, usually a reserve of rainwater collected from a roof or other catchment area. People have been storing water in cisterns for thousands of years. Cisterns can be either above or below ground, and they come in a range of sizes and shapes, with varying features. They can include tanks, pipes, and enclosed portions of buildings. Many people use cisterns to back up their regular water supply or as their primary source of water.

What are the benefits of cisterns?

Save Money
Watch your water bill decrease as you harvest your own water. City of Seattle residents are charged fees for both the potable water they use and the related sanitary sewer treatment they need to treat used water. By utilizing your own rainwater you save money on both types of fees.

Conserve Water
As competition for water grows between opposing interests – farms, salmon, urban populations – the need to conserve water increases. Combine a rapidly increasing population with lower annual rainfall, higher temperatures, and decreased snow pack, and the demand for potable water increases dramatically – putting greater pressure on municipal water supplies. Cisterns help reduce the demand on municipalities’ potable water systems and decrease the need for using these shared reservoirs of water.

Help Prevent Stormwater Pollution
Rainwater harvesting is also effective in reducing stormwater runoff pollution. When rain falls it immediately picks up pollutants which are carried into storm drains and then into streams and other bodies of water. Collecting stormwater from rooftops and directing it to cisterns decreases the volume and rate of runoff. During extreme rain events, the Seattle’s combined sewers fill to overflowing, pouring into the Puget sound without full water quality treatment. Removing rainwater from the combined sewer systems and redirecting it to cisterns lowers peak flows and reduces the amount of pollutants that find their way into our natural water bodies.

Enjoy The Benefits Of Rainwater
Rainwater is known as the “gold standard” in water quality. Rainwater is more oxygenated, is naturally pH-balanced, and is free of chlorine and additives. Rainwater increases plants’ ability to access nutrients by lowering the soil’s pH.

Green Building Credits
Trying for green building certification? Many green building systems offer credits for cisterns, helping your project reach certification goals. Examples of systems that offer these credits are LEED (Leadership in Energy and Environmental Design) as well as Built Green which is a green building program developed by the Master Builders Association of King and Snohomish Counties (in partnership with local governments).