- Q.The municipal storm drainage
system in our city shares pipes with the sewer system.
During heavy rainstorms, water backs up from the
municipal drain line into a customer’s
basement floor drain. Is there any type of check valve
that can be installed in the drain line to prevent
this?
A.Master plumber Rex
Cauldwell responds: First of all, be sure that
the local water department and building authorities
are aware of the problem and see if they can
propose a solution.
If the local municipality is unable to help, you
have two choices. In either case, you’ll
need to cut open the floor slab. If all you want to
do is stop stormwater (or worse) from coming into
the basement via the floor drain, you can install a
backwater valve in the drain line. Backwater valves
are available for about $40 to $60 from Canplas
Inc. (888/461-5307) and Oatey (800/321-9532;
www.oatey.com). Most backwater valves are available
with sleeves and access panels so that they can be
installed under concrete and still be accessible
for maintenance.
If you want the basement to drain even during a
heavy rainstorm, you’ll need to remove the
floor drain and install a sump pump. Remove the
existing drain, but leave the trap. Dig a hole for
a plastic bucket or sump kit, and then install a
submersible sump pump. Connect the sump
pump’s two-inch discharge connection to
the existing drainpipe under your slab, using
watertight threaded or glued fittings. Since the
sump pump includes a check valve in its discharge
fitting, stormwater will no longer be able to back
into the basement from that location. The sump pump
will be able to pump out under pressure any liquid
that flows into the sump, even when the utility
drains are full.