Building in vacant or underused areas in existing neighborhoods, called infill development, can significantly cut down on home water consumption and pollution, nonprofit Circulate San Diego said Monday in a report.

Infill homes tend to have smaller lot sizes and use less water for landscaping, which can account for up to 70 percent of household water use, according to Circulate. They also use less impervious surfaces, such as driveways, allowing more water to seep into the ground and avoid polluted storm water runoff.

Building new lots far from established urban centers requires new water infrastructure, including lengthy pipes to carry water. Those pipes leak more often, cost more and require more pressure than the shorter pipes that can be used in infill homes. Infill also encourages replacement of older, leaky pipes.

Circulate said local municipalities and SANDAG have adopted policies to encourage infill development, but that land use entitlement remained a politically sensitive issue.

“Abstract policies purporting to support infill development are not alone sufficient,” Circulate said. “For the water benefits of infill development to be achieved, local leaders must provide leadership and actually approve the infill projects contemplated by the region’s various planning documents.”

Circulate formed last year after Move San Diego and Walk San Diego merged.