Water Meters in Krakow - why must they be exchanged every 4-5 years?

My partner recently told me that our water meter will need to be swapped out - at a cost of 400 zł. I've never heard of such a requirement before - is it a national mandate, or is it unique to Krakow? And what is the reason for this? Is it about accuracy, or simply a way for the government to fill its coffers?

It's scam. A politician was bribed by a company (possibly his/her friend's company) and they enforced the law in Krakow (not sure if it applies to whole Poland) to extort money from its residents and force them to buy things they don't want.