According to the Natural Resources Defense Council, one of the biggest culprits of water pollution is runoff from homes. The source? Impervious surfaces like cement, which directs water onto roads and rivers, which then picks up toxic chemicals, dirt, trash and disease. Choose wood decking and interlocking bricks and paver stones for walkways instead of concrete. This allows water to drain into the soil. And if you can redirect downspouts away from driveways and onto grassy areas, that also helps prevent unnecessary water runoff.