Hard water - not filtered by water board?
 

Have you got your water already tested on hardness. If not, do it now. Maybe you should consider a water softener? Read the reviews on https://iwaterpurification.com/best-...tener-reviews/ . Personally, I have one and it is brilliant. We live in a hard water area so the improvement is significant, much more pleasant to shower / wash in, no limestone marks on sinks etc and washing machine, kettle etc stay like new.