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New brass water mixers release lead.
When the water is still in your mixer some lead is transferred to the water.
In order to reduce the risk of lead being included in the cold water you intend to drink or use for cooking, you should run the tap and drain away a few decilitres.
Boverket thinks that you should let the water run through the mixer until the water gets cold and fresh before you drink it.
Legionella bacteria can thrive in pipes if nobody uses the water for a long time.
If the bacteria enters the lungs you can become sick.
But drinking the water is not dangerous.