Reverse osmosis (RO) uses a semi-permeable membrane and relies on osmotic
pressure to force the water thru. It does a great job of blocking heavy metals, minerals and some organic
compounds due to the tiny pores in the membrane. However there is a drawback to this system. Just as a fine
sieve gets easily plugged up with small particles, so does this system. The damming with contaminants slows down
the filtering process and its effectiveness.
The RO is not very effective in removing low-molecular weight, volatile organic compounds (VOCs) such as chlorine,
MTBE, bromoform and trihalomethanes. That is why RO systems require pre and post carbon filters.
Also note that damaged membranes are not easily detected. The fouling of membrane is not controlled easily.
Fluoride removal is dependent on temperature and pH level. An acidic water level can drop fluoride removal from 90%
to below 50%. Without professional water testing, there is no real way of determining the effectiveness of the RO
system. High monitoring and installation costs, wasted water for flushing the system frequently, replacement of
expensive filters prove this system to be very costly in comparison to others.
See next page for a better solution