The first water from the tap is stagnant and contains lime scale

Hello everyone,

We have been living in our new build for a few months now and have noticed that the first cold water in the morning from the tap (whether in the kitchen or bathroom on the ground/upper floor) always tastes very stale and is also very hard despite having a water softener system. If I let the first 300-400 ml of water run, it tastes normal and the lime content gradually decreases. I wonder if this is normal because of the standing water in the pipes overnight or if something is wrong with the plumbing installation. The test kits for water hardness also say that the water should be run for a minute first. But in everyday life, that is not really practical and also quite a waste of water. My expectation would actually be immediate sparkling water quality and normal taste. What do you think could be the cause?

By the way, the water softener installed is a BWT Perla One. We also have a Conel CLEAR 2.0 backwash filter. When I activate it freshly, it has no effect on the above problem. We also have a Grundfos Comfort PM circulation pump that runs once daily for a few minutes. The domestic hot water storage is the WAS ECO 165l, which is integrated with our Weishaupt LS8-B heat pump.

Thanks in advance for your opinions!

Why is the water standing still, do you have no circulation? Stagnant water, then I would also check your descaling system, so that nothing is rotting inside.

Is the first half liter really more lime-containing than the rest (measure with the kit from the system!), or is that just your subjective perception? If descaling is done relatively strongly, it can also be dissolved carbonic acid (keyword lime-carbonic acid equilibrium).

Why is the water standing still, don’t you have circulation? Stagnant water, then I would also check your descaling system, so it’s not rotting inside

Circulation for cold water? Luxury, luxury.

Is the first half liter really higher in lime content than the rest (measure with the kit from the system!), or is that just your subjective impression. If it is descaled relatively strongly, it can also be dissolved carbonic acid (keyword lime-carbonic acid equilibrium).

I measured it. In the beginning, it is about 6-7 °dH and then settles at the target value of 3-4.

Why is the water standing still, don't you have circulation? Stagnant water, then I would also check your descaling system to make sure nothing is rotting inside

It probably shouldn't be the system itself, because coincidentally it has already been replaced once with a completely new one and the problem existed with both.