Growing plants near septic system?

Probably OK. the leach field is to disperse the water from the plumbing, sinks, shower, washing machine, dish washer, toilet. If the leach field never gets surface wet during dry weather, therefore is operating correctly, then should be no problem. I would avoid deep rooted plants, more that they may put roots down into the leach field tiles and clog them. also DO NOT use a tractor or deep rototiller over the leach field due to weight of tractor and depth of tiller teeth perhaps hitting tiles. the tiles should be deeper, about 2 feet in most areas. the soil should neutralize any harmful bacteria from the leach field. do not put garden over the septic settling tank. If choice perhaps plant elsewhere, but if not, go for it. Maybe avoid root foods, carrots, potatoes, etc.

Good question; Kelly covered the issues. For a more in-depth answer; check out Septic systems-planting