www.bayareaperviousconcrete.com: “To answer your question about paving under the drip line, see the photo below. I bit closer than I would normally care to go but the tree was surrounded that closely by impervious paving before, so it will only do better with pervious. In standard slabs water that gets under the slab tends to stay there for a long time and attracts roots. As you know roots go where the water is; since the water that falls on the pervious is allowed to infiltrate deep into the soil, that’s where the roots will go.   As for swimming pools it’s somewhat of a mixed bag. The standard pervious surface has quite a bit more grip than a troweled concrete surface without having an uncomfortable cheese grater type surface.  On the other had we’ve avoided using pervious for backyard applications (patios/pools/paths) due to the fact that it cannot be pumped (to thick) and has a short working time. Not saying it can’t be done, but it gets tricky and drives the cost up.”]]>