Watts FMRO4G-ERP-75, Installation, Operation And Maintenance Manual

Your Reverse Osmosis System:

Osmosis is the process of water passing through a semi 

permeable membrane in order to balance the concen-

tration of contaminants on each side of the membrane. 

A semi permeable membrane is a barrier that will pass 

some particles like clean drinking water, but not other 

particles like arsenic and lead. 

Reverse osmosis uses a semi permeable membrane; 

however, by applying pressure across the membrane, it 

concentrates contaminants (like a strainer) on one side of 

the membrane, producing crystal clear water on the other. 

This is why RO systems produce both clean drinking wa-

ter and waste water that is flushed from the system. This 

reverse osmosis system also utilizes carbon block filtra-

tion technology, and can therefore provide a higher quality 

drinking water than carbon filtration systems alone. 

Your system is a four stage RO which is based upon sep-

arate treatment segments within the one complete water 

filtration system. These stages are as follows:

Introduction and General Safety

Stage 1  
Sediment filter, recommended change 6 
months.

The first stage of your RO system is a five micron 

sediment filter that traps sediment and other par-

ticulate matter like dirt, silt and rust which affect 
the taste and appearance of your water. 

Stage 2  
Carbon filter, recommended change 6 months

The second stage contains a 0.5 micron carbon 

block filter.  With 20,000 Gallons capacity to 

ensure that chlorine, chloramines and other ma-

terials that cause bad taste and odor are greatly 
reduced. This filter also reduces Cyst

Stage 3 
Membrane, recommended change 2-3 years.

Stage three is the heart of the reverse osmosis 

system, the RO membrane.  This 75 Gallon per 

day semi permeable membrane will effective-

ly take out TDS & Sodium and a wide range of 

contaminants such as Percholate, Chromium, 

Arsenic, Copper, Lead as well as Cysts, such as 

Giardia and Cryptosporidium.  Because the pro-

cess of extracting this high quality drinking water 

takes time, your RO water treatment system is 
equipped with a storage tank.  

Stage 4 
Carbon in-line filter, recommended change 6 - 
12 months.

The final stage is an in-line granular activated car-

bon (GAC) filter.  This filter is used after the water 

storage  

tank, and is used as a final pol-

ishing filter.  

Note:    Filter & Membrane life may vary based upon local 

water conditions and/or use patterns.

System Maintenance

Just because you can not taste it, does not mean that it 

is not there. Contaminants such as Lead, Chromium and 

Arsenic are undetectable to the taste.  Additionally, over 

time if you do not replace the filter elements, other bad 

tastes and odors will be apparent in your drinking water.  

It is important to change out your filters at the recom-

mended intervals as indicated in this system manual.  

When replacing the filter elements, pay special attention 

to any cleaning instructions.