Rain Barrel–Urban Garden Stormwater Management Performance

Accelerated stormwater runoff creates environmental problems in many urban communities. Methods for reducing this runoff are available, but most do not work well if soils are poorly drained. Analysis of a rain barrel implementation strategy that diverts only roof runoff, for which there is a beneficial garden use, is presented and illustrated with a case study application. This approach reduces operation to the growing season and requires that the rain barrel function to benefit the garden and to reduce runoff, but may improve homeowner acceptance and operation. General methods for quantifying and bounding system effectiveness are illustrated. Case study results indicate that a 50-gal. (189-L) rain barrel connected to 25% of a $\mathrm{2,000}\text{-}{\mathrm{ft}}^2$ ($186\text{-}{\mathrm{m}}^2$) residential roof and serving a $150\text{-}{\mathrm{ft}}^2$ ($14\text{-}{\mathrm{m}}^2$) garden in Cleveland Heights, Ohio, would reduce the total roof growing-season runoff by 2.4–5.4% and the total annual roof runoff by 1.4–3.1%, depending on the irrigation strategy applied. Increasing garden and barrel size could increase the annual runoff reduction to 7.4%, but barrel capacity constrains additional reductions. These results illustrate the stormwater management limitations of rain barrels used in the case study location. The degree to which the analytical methods and results may be generalized to other communities is discussed.