Filtration-purification levels and stages

Drinking water treatment solutions at different levels:

Level 1: Fine particle filtration / Level 2: Micro filtration

Fine particle filtration and micro filtration can be considered as a pre-treatment to remove particles like sediment, algae and large bacteria. We don’t consider it as a complete filtration process on yachts.

Level 3: Ultra filtration (UF) or Ultra violet (UV)

To overcome the risks of pathogenic (bacteria, virus, algae etc.) contamination Ultra filtration (UF) in combination with an Activated Carbon filter is sufficient. This treatment solution doesn’t require electrical power, doesn’t use any chemicals and doesn’t reject water and can be installed under your sink without efforts nor doesn’t require a lot of space.

Another solution on this treatment level is the combination of an UV-lamp (sterilizer) with Activated carbon. Similar sizes, though electrical power is needed.

While the UF or the UV lamp respectively sterilize the pathogens, the activated carbon ensures the elimination of odor and taste.

Both options require attention regarding cartridge replacements according to the diverse water sources and particular when they are not permanently in use.

Level 4: Nano filtration/Level 5: low pressure reverse osmoses (Low RO)

To eliminate also chemical contamination such as heavy metals, pesticides, micro plastics and pharmaceutical residues a higher level of treatment is needed. For this, nano filtration or low pressure RO are appropriate. Not only for yachts operating in sea water which use watermaker treated seawater as well as shore based water sources as raw water source, but also for yachts operating in fresh water (lakes and rivers) can use these filtration systems as raw water input for the filtering/purifying into superior quality of drinking water.

Nano filtration is based on the same physical principals as RO though limited to a molecular cut off weight of 100-200 Daltons. Commonly found contamination below that weight is based on aquatic salts and doesn’t exist in your shore based water source or has been treated by your water maker. Nano filtration requires less electrical power and rejects less water (around 35 %) than low RO (40-50 %).


The different stages of a complete filtration and purification process

Complete solutions come in general in three stages based on pre-filtration (micro filtration and activated carbon adsorbtion), purification (Nano, ROlow) and post-filtration (re-mineralization). Under-sink purifying/filtration units producing between 100-165  l are sufficient to provide a yachts crew, owners and guests or 50-130 l for a family/office with drinking water in a superior quality compared to bottled water while having a minimal environmental footprint. Further on the final fourth stage of distribution provides convenience.

The more advanced solutions on this treatment level are equipped with sensors which communicate the technical status of the unit regarding maintenance intervals.

1. PRE-FILTRATION (aims to protect the purification membrane):

  • Micron filter and Adsorption filter

A string wound filter element with a pore size of 5 micron is sufficient to eliminate harmful solids. An activated carbon (AC) filter adsorpts chlorine and eliminates odor and taste.

2. PURIFICATION (eliminates contamination to molecular cut off weight of 200Daltons)

To eliminate above discussed contamination, Water without Waste recommends Nano or low RO purification. Technically the same process as found in a watermaker yet on a lower pressure level, sufficient for fresh water.

For a single drinking water outlet a point of use system purifies on demand. All purifiers in our product line have automated flush mechanism, direct flow and read out required maintenance.

3. POST-FILTRATION (re-introduces essential minerals)

After the purification process the permeate tends to be slightly acidic (subject to raw water quality) and is chemically tasteless. To have a healthy alkaline ph level above 7 the permeate passes through a cartridge filled with 8 different minerals (Ca, Na, K, Cl, Mg, Fe, Zn, Cr).  According to your water pressure and flow rate the permeate picks up these minerals and becomes healthy & tasty drinking water.






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