U trap

Dear all,

Is it consider a good design to install U trap for drain pipe (such as

floor drainage in a Liquid mixing room and basin drainage in change room) ?

Thank you

Normally this type of design is considered as per clean room design. This is
to ensure there is no contamination entering from the outer area.
However the stagnant water in the U loop is a matter of concern, hence
proper cleaning and sanitization of the drainage is more important to be


There is a regulation from the municipalities that
require us to have what we call a “P” trap after each drain - if we do
not install these we will not have our facilities approved for occupancy
as a part of the building permit process

As a result we have a standing maintenance task of sanitizing the drains
in our process areas on a regular basis

Each “P” trap is installed immediately below the floor drain and the
purpose is to prevent sewer gasses (and other types of contamination)
from getting back into the rooms above the floor level

Additionally, we install “clean out” ports which are capped and sealed
access points which allow us to access the drains should they become
clogged for any reason

The floor drains are also equipped with flushing devices which either
constantly trickle a small amount of water to each drain or on a
periodic basis water is flushed to each drain automatically through a
tube (~5-6mm diameter) to ensure that the water trap created in the trap
does not evaporate. This water does contain some chlorine from the
municipal water system, but we supplement the process with the
maintenance of the drains on a periodic basis.

Cleaning usually is a simple task of pouring a quantity of a sodium
hypochlorite (or other approved sanitizing agent) solution down each