Abstract: A fluid drainage and filtering system composed of stocked in-drains and spacers wrapped serpentine fashion with a non-woven fabric of fluid pervious material. Each in-drain has a dimpled core sheet defining spaced lands and surrounding valleys and a thickness related to the pitch distance between these lands. Each spacer has outer sheets of about 1/2 the thickness of the core sheet, but also having lands surrounded by valleys. The pitch distance of the lands in these outer sheets is also about 1/2 that of the thicker core sheets so the spacers and in-drains do not tend to nest into one another when the system is installed.

Abstract: A leaching field is constructed from a plurality of rectangularly shaped elongated geotextile covered in-drain core elements provided alongside one another. The elements have equally spaced fold lines extending laterally across their adjacent semi-folded portions so that a stack of such elements in a flattened condition occupies a minimal space whereby these elements can be readily transported to the site. When expanded honey comb configuration is achieved so that a self supporting in-drain structure greatly facilitate construction of the leaching field without the need for templates and the like to support the structure during the filling of the voids between the adjacent in-drain elements themselves. If desired, expendable stakes may be used to support the in-drain assemblies in an optimum configuration.

Abstract: A leaching field is prepared by fitting together segments of PVC pipe in the manifold configuration that defines a plurality of outlets, each outlet having a unique in-drain configuration with an internal core and external non-woven geotextile fabric envelope. The method calls for supporting these relatively flexible in-drains with a template while space between the in-drains is filled with sand or the like. In a further embodiment each of the in-drains is fitted with a stand pipe that is useful to backflush the in-drains periodically.

Abstract: A wastewater treatment system provides a leaching field that may be of conventional configuration or may include certain unique features, the present invention relating to a subterranean horizontally oriented in-drain below the conventional leaching field that is adapted to be fed with a soapy solution to improve the biodegradation under anaerobic conditions heretofore possible only with wastewater treatment systems adapted to separate gray water from black water sewage.

Abstract: Separating domestic waste water for aerobic filtration of black water and subsequently combining the filtration with grey water provides a convenient source of carbon and anaerobic matter for biological dentrification of nitrates in a filtration system of anaerobic atmosphere achieved biologically through normal decomposition. Improved filter means for the black water includes alternating layers of stone and sand, the latter being well ventilated to maintain at least slight acidity (pH=4).