I could not decide where to put this so I put it here. I have a couple of questions about building a rain garden. Let me start by saying I have never built a rain garden before but I am very well aquianted with proper landscape construction techniques for planting beds, fountains, ponds, and retaining walls. My questions are this How close is to close when putting a rain garden buy a house? Would it be advisable to under drain the rain garden to make sure it can handle the occasional 6+ inch rain Our average rainfall is 47 inches per year and you can expect at least 1 -2 rains a year that will dump more than 6 inches in a 24 housr period. Interestingly enough most guys out here know almost nothing about rain gardens.