Source of Hot Water in the Capital Area

The hot water supply for the capital area is primarily derived from two sources. One resource is the low-temperature geothermal areas in Reykjavík and Mosfellsbær, such as Laugarnes and Elliðaárdalur. The other resource is the geothermal cogeneration power plants at Nesjavellir and Hellisheiði. 

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In the past, each neighborhood in the capital area had either hot water from wells or geothermal cogeneration power plants. Nowadays, it's increasingly common to switch one type of water supply to another, often temporarily, to suit the operation's needs. This is usually done to let the geothermal reservoir in Reykjavik rest, ensuring their operation remains as sustainable as possible. 

The main difference between these two types of water, that is from wells and then geothermal cogeneration power plants is the silica content. Silica-rich hot water forms deposits that settle on taps and elsewhere as it cools. The highest silica content is found in the hot water from the wells in Laugarnes, where the water is the hottest. On the other hand, the water from Nesjavellir and Hellisheiði is heated groundwater with low silica content. 

The map shows how the hot water is distributed throughout the capital area during an average winter.  

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