WHOLE HOUSE CARBON FILTRATION SYSTEM • 7
Special Attention for situations where a Filter and a Softener are installed together:
When a whole house filter and a softener are installed side by side, the preferred approach is to run a
separate drain line from each unit all the way to the point of termination. If this is not done, there is the
potential for drain water from the filter to back feed through the softener and overfill the brine tank,
especially when drain lines are run overhead. (Please note that back feed goes only into the brine tank, not
the service line.)
If circumstances require you to tie the drain lines together, please use one of the following methods to
avoid back feed issues:
Option 1
: Run the drain lines from both systems to the point of termination, and tee them together before
the air gap. (See figures below)
Option 2
: Install a PVC check valve with a light spring on the Softener side to prevent back flow to the
Softener. (See figure below)
WATE
R IN
TREATED
WATER OUT
2 SEPARATE DRAIN LINES
TO AP
PROV
ED D
RAIN
LOCA
TION
WITH
AIR G
AP
FILTER
SOFTENER
Option 1 - Part A
2 SEPARATE
DRAIN LINES
AIR GAP
APPROVED FLOOR DRAIN
TEE
Option 1 - Part B
FILTER
SOFTENER
SPRING CHECK ON DRAIN
LINE AFTER SOFTENER
WATE
R IN
TREATED
WATER OUT
TO AP
PROV
ED D
RAIN
LOCATION WITH AIR GA
P
Option 1 - Part A
Option 1 - Part B
Option 2
