GENERAL
Do not use with water that is microbiologically
unsafe or of unknown quality without adequate
disinfection before or after the system.
Systems certified for cyst reduction* may be
used on disinfected waters that may contain
filterable cysts.
*NSF/ANSI Standard 58 certified to reduce cysts such as
Cryptosporidium and Giardia by mechanical means.
Filter must be protected against freezing, which can
cause cracking of the filter and water leakage.
Because of the product’s limited service life and to
prevent costly repairs or possible water damage, we
strongly recommend that the bottom of all plastic
housings be replaced every five years for clear and
ten years for opaque. If the bottom of your housing
has been in use for longer than this period, it should
be replaced immediately. Date the bottom of any
new or replacement housing to indicate the next
recommended replacement date.
NOTE:
• Your water must be within required limits for satisfactory
operation. If not, your membrane life may be shortened and
your warranty will be voided (see Specifications on page 1).
• This reverse osmosis system will not protect against disease-
causing bacteria or remove naturally-occurring harmless
bacteria.
• Install on cold water line only.
• Do not use wicking or sealer to fit connections into the cap of
the filter. Plumber tape is recommended.
• Make certain that installation complies with all state and
local laws and regulations.
• The replacement cartridges and reverse osmosis element
included with this system have limited service lives. Changes
in taste, odor, and color of the water being filtered indicate
that the cartridge should be replaced (see Replacing the
Pre- and Post-Filters on page 9, and Replacing the osmosis
element, on page 10).
• After prolonged periods of non-use (such as during a
vacation) it is recommended that the system be flushed for 5
minutes before it is used.
• A drinking water cartridge may contain carbon fines (very
fine black powder). After installation, flush the system for 5
minutes to remove the carbon fines before using the water.
• It is recommended that you run the tap at least 20 seconds
prior to using water for drinking or cooking purposes.
• The contaminants or other substances removed or reduced
by this water treatment device are not necessarily present in
your water.
RO MEMBRANE PRECAUTIONS
Chlorine will destroy the GRO-EN reverse osmosis
element. If you use the GRO-450 with a chlorinated
or periodically-chlorinated water supply, it is
ABSOLUTELY NECESSARY to use a carbon pre-filter
(included with the system). The carbon pre-filter
should be changed at least every 12 months to avoid
chlorine bypass.
HOWREVERSE OSMOSIS WORKS
The GRO-4550 Reverse Osmosis (RO) System uses a semi-
permeable membrane to reduce dissolved salts and minerals,
improving the taste and odor of your water. The RO membrane
is made of layers of micron-thin film wound around a hollow
center core. Water molecules can pass through the membrane,
but dissolved salts and minerals are rejected.
The GRO-450 Reverse Osmosis System features 4-stage filter
action. Your water supply is pre-filtered to reduce dirt and
chlorine that may foul the membrane. The RO membrane
separates this pre-filtered water into PRODUCT WATER and
DRAIN or REJECT WATER. Incoming water pressure forces
the product water through the membrane and into the storage
tank. Dissolved solids and other contaminants cannot pass
through the membrane and are sent to the drain as reject
water. When you open the drinking water faucet, product water
is drawn from the storage tank through an activated carbon
post-filter, providing you with cleaner, great-tasting water.
For each gallon of water produced, several gallons are
discharged as reject water. The storage tank can hold up to
2.8 gallons (10.6 L) of water at a time, for drinking and cooking
needs. When used under the Specifications on page 1 of the
manual, your Reverse Osmosis membranes should last 48-60
months.
BASIC INSTALLATION PROCEDURE GUIDELINES
•For standard, under-sink installation on 3/8-inch (10 mm)
steel, brass, or copper cold water line.
•Please read all instructions and precautions before installing
and using your GRO-450.
• Numbered diagrams correspond with numbered steps.
PRECAUTIONS
INSTALLATION
• Read all installation and operating instructions before
installing and using your RO system.
• Numbered diagrams correspond with numbered steps.
1. Installing the Water Supply Adapter
The supply adapter fits 1/2 NPS threaded connections. If local
codes permit, it may be used to connect the GRO-2550 to the
cold water supply line. If local codes do not permit the use of
the supply adapter, alternate connectors can be obtained from
your local plumbing wholesaler.
Directions:
(A) Turn off cold water inlet supply line. If cold water line does
not have a shut-off valve under the sink, you should install
one.
(B) Turn on the cold water faucet and allow all water to drain
from line.
(C) Disconnect cold water line from the bottom of main faucet.
(D) Install the water supply adapter into the cold water line.
NOTE:
• To make sure no chlorine is present in the water that reaches
the membrane, you may want to use a chlorine test kit to
check the brine/reject water that flows from the membrane to
the drain. No chlorine should be detected.
• The GRO-50EN element is resistant to naturally-occurring
bacteria.
RAIN GRO-475 Installation and Operation Manual • 3
