An Infrastructure Alternative to Outside Drop Connections

Aug. 13, 2020
The RELINER®/Duran Inside Drop System was designed to control flow using simple, cost-effective, readily available components.

Sewer drops in manholes have traditionally been constructed using a variety of techniques that have proven troublesome over time. Outside drops are expensive to construct, prone to clogging and failure, and difficult to access for inspection, cleaning, and maintenance. Interior tee fittings require the inlet pipe to extend into the manhole with the tee and drop pipe protruding far into the interior of the manhole. This can interfere with manhole access and it is difficult to properly secure the pipe. Inspection and maintenance are difficult.

The RELINER®/Duran Inc. Inside Drop System was designed to address all of these issues and control flow using simple, cost-effective, readily available components. The system consists of a fiberglass drop bowl that is bolted to the manhole wall just beneath the high-level inflow pipe. Stainless-steel pipe support brackets are used to attach the drop pipe to the wall. The drop bowl does not touch the incoming pipe and protrudes minimally into the structure. The resulting drop pipe is just off the manhole wall and securely fastened. A flexible coupler is used to connect the drop pipe to the drop bowl, and a bend is installed at the pipe base in the manhole invert. An optional force line hood is available for high-velocity applications.

The system is easy to install and allows the drop to be cleaned and inspected from above. The system is available to accommodate internal drops ranging from 4” to 24” in diameter. WW

RELINER®/Duran Inc. provides simple, cost-effective, durable products for use in the wastewater and construction industries. To learn more, visit


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