See also:
22 1435 - Roof Drains
33 4300 - Water Harvesting Systems
33 4800 - Subsurface Retention/Detention Systems
Jay R. Smith Mfg. Co. 
Manufacturer of commercial plumbing and drainage products such as fixture supports, floor, roof and trench drains, cleanouts, interceptors, hydrants, backwater valves (Flood-Gate), Ultracept® Oil/Water Separator, Remediator® Grease Treatment System & other specialty plumbing products.
Mifab Manufacturing 
Access doors, valve boxes, grease, oil, solids, specialty interceptors, trap seal primers, fixture supports, floor, roof and trench drains, cleanouts, wall and ground hydrants, floor sinks, backwater valves, water hammer arrestors, C-PORT pipe supports, backflow preventers, pressure reducing valves, gauges, siphonic roof drains, no hub couplings and fabricated stainless steel trench and floor drains.
Victaulic Company of America
Since 1925, the world leader in grooved and plain-end mechanical pipe joining systems. Victaulic offers complete, start-to-finish solutions that anticipate a project’s every need. The Victaulic grooved-piping method accommodates most piping materials, including lightwall, standard and extra-heavy duty steel, stainless, aluminum, ABS and other plastics, as well as underground-and waste-treatment process piping. ISO 9001 certified.
Watts 
Since 1874 a leading manufacturer of water safety & flow control products, backflow prevention devices, water quality & conditioning products, specification drainage products, brass & tubular products, control valves, potable PEX plumbing products, Quick-Connect Push Fit Solutions, and Custom OEM Products.
Zurn Plumbing Products Group
is a family of specialty companies dedicated to producing "engineered" roof-to-basement water and water drainage controls for the residential, commercial, industrial and institutional building markets.