HDPE Pipe We sre stocking distributors of ADS - Advanced Drainage Systems High Density Polyethylene (HDPE) Pipe. N-12 Pipe comes in sizes 4"-60". We currently stock 12" through 24" We also stock 4" Single Wall coils of solid, perforated, & sock pipe, along with all of the basic 4" single wall fittings. ADS also produces a wide variety of fittings & grates. They also supply Nyloplast® Surface Drainage Structures. All of these items can be special ordered at Midwest Municipal Supply, Inc.