Rather than altering the topography of a site and installing pipes and grates, the most effective drainage systems take their lead from the existing lay of the land. Runoff permits pollutants to enter the water table, allowing them to concentrate in drinking water supplies, as well as impacting infrastructure, ruining septic systems and permitting erosion from acid rain. Reducing the amount of pollutants that may enter groundwater may also mitigate the damaging effects of runoff. By observing and using existing stormwater patterns, natural and cost effective management systems can be put into place. The use of retention trenches and infiltration basins, as well as selective choices of materials, can create low profile and highly efficient drainage systems, which simultaneously add value to the neighborhood. It must be noted that suburban and urban sites must have different management regulations. The usage of natural features impedes the high- density growth necessary for urban communities.