For many years experiments with electrodialysis units of different designs have showed that large advertising of reverse electrodialysis (EDR) does not have the necessary basis. Sedimentation, mainly compound of calcium, takes place to one or other extent in any case. Asymmetrical electrodialysis (EDA) is proposed which in domestic units, with the capacity up to 50 Uh, showed itself to advantage quite effectively. Among other innovations used in these units there are composite electrodes which are metal-oxidcarboplastic and spacers of new design. More than 200 EDA units sold to different countries of the world for desalination of water with salt content (TDS) 1-8 g/l. However, the market of seawater desalination is much larger than the brackish water market. That is why the Company's efforts were forwarded to this direction. The principle of electrodialysis is the basis of a new technology. The motivation of the choice is as follows. Main disadvantages are: developed system of water pretreatment (up to 7 stages) and frequent membrane replacement (sometimes after 6 months). The cost of membranes is 50% of the equipment's cost. So, after 2 years of system's operation the cost is doubled. However, at present for desalination of large water volumes, reverse osmosis units have indisputable advantages. They are: a) a developed system of engineering provision; b) work experience and after-sale services; c) low cost of electric power (for high salinity ocean water); d) psychological factor that these systems are used for more than 20 years. All the advantages of reverse osmosis disappear if you speak about using domestic systems where qualified engineering provision is impossible. The main advantages of electrodialysis when used for domestic systems (for cottages, offices, yachts, etc..) are: a) electrodialysis system EDIS "SW'' allows to treat water with salt content up to 45 g/l; b) capacity - 45-1000 gal/d; c) presently the period of continuous unit operation is more than 3 months.