Reverse Osmosis

Reverse osmosis removes contaminants from water by using pressure to force the water molecules through a semi-permeable membrane. During this process, the molecules are filtered out and flushed away, leaving clean and delicious drinking water.

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Reverse Osmosis System

Reverse osmosis is a water purification process that pushes water through a partially permeable membrane to separate ions, unwanted molecules and larger particles from drinking water.
Within the whole reverse osmosis system, there are four main stages:

  • First, the water passes through carbon and sediment filters to remove any dirt or chlorine that could damage the membrane. This is known as pre-filtration.
  • The water is then pushed through the membrane which can filter out any smaller, dissolved particles.
  • This filtered water then enters a storage tank where it will remain until an outlet is opened for use.
  • Before flowing through the outlet, the water from the tank will pass through a final post-filter to ensure the highest level of water quality.

Reverse Osmosis Filter

While the main attraction of a reverse osmosis system is the permeable membrane, the whole system can contain up to five different types of filtration.

A standard reverse osmosis water system includes a sediment filter to remove physical contaminants like dirt along with an activated carbon filter and the reverse osmosis membrane. The filters are either called prefilters or postfilters depending on where they are placed in relation to the membrane. For example, if the water passes through the sediment filter before it comes to the membrane, this would be a prefilter.

By combining all of these filtration stages, a reverse osmosis system is considered one of the most efficient filters on the market.




Reverse osmosis works by passing pressurised water through a semi-permeable membrane which contains thousands of tiny pores that filter down to 0.0001 microns. These pores block contaminants but allow the water to flow through.

The idea was originally inspired by sea birds who have a membrane in their throats that repels salt and allows them to drink water safely from the ocean.

The fresh water that flows through the filter is called the permeate while the water that contains the substances blocked by the pores is known as the waste or brine.

Within the system, the water is then divided into two streams: one stream carries the filtered water to wherever it is needed while the second takes the pollutants away from the supply. A reverse osmosis filter is unique in that it does not just trap the contaminants, but it actively flushes them away.

Reverse Osmosis Systems will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.

The process of reverse osmosis reduces salt, minerals and any other impurities. … RO systems are less efficient than water softeners, so they’re usually installed at a single point-of-use, like a kitchen sink, rather than used for the whole house.

RO removes lead from water and frees people from many diseases such as high blood pressure, nerve damage and low fertility. Drinking reverse osmosis water can also eliminate risks of brain damage and anemic conditions, especially in children.

RO water which doesn’t contain enough minerals, when consumed, leaches minerals from the body. This means that the minerals being consumed in food and vitamins are being urinated away. Less minerals consumed plus more minerals being excreted causes serious negative side effects and big health problems.

Portawater Uk Ltd has been installing softners for both commercial and domestic for more than 35 years.