A subsurface fluid distribution system for sewage effluent and irrigation water utilizes one or more arrays of serially connected leaching chambers. Each leaching chamber is a double-walled construction of arch-shaped cross section with an open bottom and closed ends. A plurality of vertically off-set openings are formed in the inner and outer walls, with the inner openings located at a higher liquid level than the outer openings to prevent clogging of the leaching chambers by either sand or root growth. The leaching chambers are connected to one another to permit fluid communication between adjacent chambers, and are installed below ground in shallow trenches that are backfilled with sand and then topped with top soil. The sewage effluent or irrigation water flows through the array of leaching chambers in an unpressurized flow. The even distribution of the fluid, both laterally and vertically, through the sand bed and then to the surrounding soil is enhanced by the capillary action properties of sand and the evapo-transpiration effect provided by the overlying plant growth.