Source of hot water in the capital area
The hot water used in the capital area is on the one hand from low temperature areas in Reykjavík and Mosfellsbær (Laugarnes and Elliðaárdalur) and the other from geothermal areas from Nesjavellir and Hellisheiði.
The map shows how the hot water is distributed throughout the capital. Residents in Reykjavík west of Grafarvogur, in Úlfarsárdalur, Mosfell and Kjalarnes normally get geothermal water from wells in Reykjavík and Mosfellsbær.
Grafarholt, Grafarvogur, Kópavogur, Garðabær and Hafnarfjörður however get hot water from Nesjavellir and Hellisheiði. In some neighbourhoods it is possible to temporarily take the water from other sources to reset the system.
The main difference of the water between districts is the amount of silicon. Silica-rich hot water forms a scab that sits on the tap-opening and on other places when it cools. Most of the silicon in the hot water comes from wells in Laugarnes where the water is hottest. The water that comes from Nesjavellir and Hellisheiði is in turn heated groundwater with small amounts of silica.
The origin and quality of water differ by region.